Citations
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This panel provides information on past usage of this interatomic potential (IP) powered by the OpenKIM Deep Citation framework. The word cloud indicates typical applications of the potential. The bar chart shows citations per year of this IP (bars are divided into articles that used the IP (green) and those that did not (blue)). The complete list of articles that cited this IP is provided below along with the Deep Citation determination on usage. See the Deep Citation documentation for more information.
342 Citations (226 used)
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USED (high confidence) P. Siani and C. D. Valentin, “Effect of dopamine-functionalization, charge and pH on protein corona formation around TiO2 nanoparticles,” Nanoscale. 2022. link Times cited: 2 Abstract: Inorganic nanoparticles (NPs) are gaining increasing attenti… read moreAbstract: Inorganic nanoparticles (NPs) are gaining increasing attention in nanomedicine because of their stimuli responsiveness, which allows combining therapy with diagnosis. However, little information is known about their interaction with intracellular or plasma proteins when they are introduced in a biological environment. Here we present atomistic molecular dynamics (MD) simulations investigating the case study of dopamine-functionalized TiO2 nanoparticles and two proteins that are overexpressed in cancer cells, i.e. PARP1 and HSP90, since experiments proved them to be the main components of the corona in cell cultures. The mechanism and the nature of the interaction (electrostatic, van der Waals, H-bonds, etc.) is unravelled by defining the protein residues that are more frequently in contact with the NPs, the extent of contact surface area and the variations in the protein secondary structures, at different pH and ionic strength conditions of the solution where they are immersed to simulate a realistic biological environment. The effects of the NP surface functionalization and charge are also considered. Our MD results suggest that less acidic intracellular pH conditions in the presence of cytosolic ionic strength enhance PARP1 interaction with the nanoparticle, whereas the HSP90 contribution is partly weakened, providing a rational explanation to existing experimental observations. read less USED (high confidence) H. Badorreck, L. Jensen, D. Ristau, and M. Jupé, “Statistical Analysis on the Structural Size of Simulated Thin Film Growth with Molecular Dynamics for Glancing Angle Incidence Deposition,” Coatings. 2021. link Times cited: 2 Abstract: For the purpose of a deeper understanding of thin film growt… read moreAbstract: For the purpose of a deeper understanding of thin film growth, in the last two decades several groups developed models for simulation on the atomistic scale. Models using molecular dynamics as their simulation method already give results comparable to experiments, however statistical analysis of the simulations themselves are lacking so far, reasoned by the limits imposed by the computational power and parallelization that can only be used in lateral dimensions. With advancements of software and hardware, an increase in simulation speed by a factor of up to 10 can be reached. This allows either larger structures and/or more throughput of the simulations. The paper analyses the significance of increasing the structure size in lateral dimensions and also the repetition of simulations to gain more insights into the statistical fluctuation contained in the simulations and how well the coincidence with the experiment is. For that, glancing angle incidence deposition (GLAD) coatings are taken as an example. The results give important insights regarding the used interaction potential, the structure size and resulting important differences for the density, surface morphology, roughness and anisotropy. While larger structures naturally can reproduce the real world in more detail, the results show which structure sizes are needed for these aspects without wasting computational resources. read less USED (high confidence) M. M. Heyhat, M. Abbasi, and A. Rajabpour, “Molecular dynamic simulation on the density of titanium dioxide and silver water-based nanofluids using ternary mixture model,” Journal of Molecular Liquids. 2021. link Times cited: 7 USED (high confidence) D. O’Carroll, J. Martínez-González, and N. J. English, “Coherency spectral analysis of interfacial water at TiO2 surfaces,” Molecular Simulation. 2020. link Times cited: 3 Abstract: ABSTRACT Classical molecular dynamic studies of anatase <101… read moreAbstract: ABSTRACT Classical molecular dynamic studies of anatase <101> and rutile <110> surfaces immersed in bulk SPC/fw water were performed to investigate the dynamic properties of the semi-mobile water layers formed thereon. Spectral analysis techniques were used to characterise and interpret the observed dynamical behaviour, including the use of frequency domain cross-correlation measures. Both surfaces exhibit distinct layering patterns, wherein molecular motion is inhibited and certain molecular vibrational modes are augmented or diminished. There is evidence that this effect is mediated by coupling of vibrational modes between the observed layers and under-coordinated surface oxygen (Obr) atoms and may play a role in the fascinating behaviour of water at TiO2 interfaces. read less USED (high confidence) D. Selli, S. Motta, and C. D. Valentin, “Impact of surface curvature, grafting density and solvent type on the PEGylation of titanium dioxide nanoparticles.,” Journal of colloid and interface science. 2019. link Times cited: 26 USED (high confidence) N. Rajabiyoun and T. Karacali, “A new approach to modeling TiO2−x-based memristors using molecular dynamics simulation,” Applied Physics A. 2019. link Times cited: 4 USED (high confidence) N. Rajabiyoun and T. Karacali, “A new approach to modeling TiO2−x-based memristors using molecular dynamics simulation,” Applied Physics A. 2019. link Times cited: 0 USED (high confidence) F. Grigoriev, V. Sulimov, and A. Tikhonravov, “Simulation of the optical coating deposition,” Advanced Optical Technologies. 2018. link Times cited: 5 Abstract: A brief review of the mathematical methods of thin-film grow… read moreAbstract: A brief review of the mathematical methods of thin-film growth simulation and results of their applications is presented. Both full-atomistic and multi-scale approaches that were used in the studies of thin-film deposition are considered. The results of the structural parameter simulation including density profiles, roughness, porosity, point defect concentration, and others are discussed. The application of the quantum level methods to the simulation of the thin-film electronic and optical properties is considered. Special attention is paid to the simulation of the silicon dioxide thin films. read less USED (high confidence) Z. Futera and N. J. English, “Oscillating electric-field effects on adsorbed-water at rutile- and anatase-TiO2 surfaces.,” The Journal of chemical physics. 2016. link Times cited: 16 Abstract: We have performed non-equilibrium molecular dynamics simulat… read moreAbstract: We have performed non-equilibrium molecular dynamics simulations of various TiO2/water interfaces at ambient temperature in presence of oscillating electric fields in frequency range 20-100 GHz and RMS intensities 0.05-0.25 V/Å. Although the externally applied fields are by one order of magnitude lower than the intrinsic electric field present on the interfaces (∼1.5-4.5 V/Å), significant non-thermal coupling of rotational and translational motion of water molecules was clearly observed. Enhancement of the motion, manifested by increase of diffusivity, was detected in the first hydration layer, which is known to be heavily confined by adsorption to the TiO2 surface. Interestingly, the diffusivity increases more rapidly on anatase than on rutile facets where the adsorbed water was found to be more organized and restrained. We observed that the applied oscillating field reduces number of hydrogen bonds on the interface. The remaining H-bonds are weaker than those detected under zero-field conditions; however, their lifetime increases on most of the surfaces when the low-frequency fields are applied. Reduction of adsorption interaction was observed also in IR spectra of interfacial water where the directional patterns are smeared as the intensities of applied fields increase. read less USED (high confidence) C. Guo, C. Wu, M. Chen, T. Zheng, N. Chen, and P. Cummings, “Molecular modeling of fibronectin adsorption on topographically nanostructured rutile (110) surfaces,” Applied Surface Science. 2016. link Times cited: 13 USED (high confidence) L. Dong, Y. Li, R. Devanathan, and F. Gao, “Molecular dynamics simulation of the structural, elastic, and thermal properties of pyrochlores,” RSC Advances. 2016. link Times cited: 21 Abstract: We present a comprehensive simulation study of the effect of… read moreAbstract: We present a comprehensive simulation study of the effect of composition on the structural, elastic and thermal properties of 25 different compounds from the pyrochlore family. We joined a repulsive potential to an existing interatomic potential to enable molecular dynamics simulations of conditions away from equilibrium. We systematically varied the chemistry of the pyrochlore by substituting different cations in the A and B sites of the A2B2O7 formula unit. The A cations varied from Lu3+ to La3+, and the B cations from Ti4+ to Ce4+. The lattice parameter increased steadily with increasing the radius of A or B cations, but the bulk modulus showed a decreasing trend with increasing cation radius. However, the specific heat capacity and thermal expansion coefficient remained almost unchanged with increasing the radii of A and B cations. It is of interest to note that Ce on the B site significantly reduces the specific heat capacity and thermal expansion coefficient, which could have implications for annealing of radiation damage in cerate pyrochlores. The present results are consistent with the experimental measurements, which suggests that these potentials are appropriate for studying the problem of interest, namely simulation of dynamical processes, radiation damage, and defect migration in pyrochlores. read less USED (high confidence) S. I. Lukyanov, A. Bandura, and R. Evarestov, “Young’s modulus and Poisson’s ratio for TiO2-based nanotubes and nanowires: modelling of temperature dependence,” RSC Advances. 2016. link Times cited: 6 Abstract: In this work molecular mechanics simulations with the help o… read moreAbstract: In this work molecular mechanics simulations with the help of interatomic potentials were employed to predict the temperature dependence of the Young's modulus and Poisson's ratio of a number of TiO2-based four-facetted nanotubes and nanowires. The temperature dependence of the Young's modulus was obtained through the calculation of the Helmholtz free energy of the system under isothermal thermodynamic conditions. The Helmholtz free energy simulations were performed in the framework of quasi-harmonic approximation as a result of calculations of the potential energy and the harmonic phonon frequencies of the system under consideration. The Helmholtz free energy calculated for the set of fixed values of the nanoobject translational period allows obtaining the minimal Helmholtz free energy at specified temperatures in the range 0–1000 K. The present simulations demonstrate that the Young's modulus for the TiO2-based nanowires decreases with the increase of the nanowire diameters, and approaches the modulus for the rutile bulk crystal from above. Also, the temperature behavior of the Young's modulus, Poisson's ratio and period for the nanotubes and nanowires are considered. This study reveals that the Poisson's ratios of the nanotubes and nanowires depend on the surface atoms chosen to measure the transverse dimensions of the nanostructures. read less USED (high confidence) N. J. English, “Diffusivity and Mobility of Adsorbed Water Layers at TiO2 Rutile and Anatase Interfaces.” 2015. link Times cited: 16 Abstract: Molecular-dynamics simulations have been carried out to stud… read moreAbstract: Molecular-dynamics simulations have been carried out to study diffusion of water molecules adsorbed to anatase-(101) and rutile-(110) interfaces at room temperature (300 K). The mean squared displacement (MSD) of the adsorbed water layers were determined to estimate self-diffusivity therein, and the mobility of these various layers was gauged in terms of the “swopping” of water molecules between them. Diffusivity was substantially higher within the adsorbed monolayer at the anatase-(101) surface, whilst the anatase-(101) surface’s more open access facilitates easier contact of adsorbed water molecules with those beyond the first layer, increasing the level of dynamical inter-layer exchange and mobility of the various layers. It is hypothesised that enhanced ease of access of water to the anatase-(101) surface helps to rationalise experimental observations of its comparatively greater photo-activity. read less USED (high confidence) S. I. Lukyanov, A. Bandura, and R. Evarestov, “Temperature dependence of Young’s modulus of titanium dioxide (TIO2) nanotubes: Molecular mechanics modeling,” Physics of the Solid State. 2015. link Times cited: 7 USED (high confidence) M. Machesky, M. Předota, M. Ridley, and D. Wesolowski, “Constrained Surface Complexation Modeling: Rutile in RbCl, NaCl, and NaCF3SO3 Media to 250 °C,” Journal of Physical Chemistry C. 2015. link Times cited: 15 Abstract: A comprehensive set of molecular-level results, primarily fr… read moreAbstract: A comprehensive set of molecular-level results, primarily from classical molecular dynamics (CMD) simulations, are used to constrain CD-MUSIC surface complexation model (SCM) parameters describing rutile powder titrations conducted in RbCl, NaCl, and NaTr (Tr = triflate, CF3SO3–) electrolyte media from 25 to 250 °C. Rb+ primarily occupies the innermost tetradentate binding site on the rutile (110) surface at all temperatures (25, 150, 250 °C) and negative charge conditions (−0.1 and −0.2 C/m2) probed via CMD simulations, reflecting the small hydration energy of this large, monovalent cation. Consequently, variable SCM parameters (Stern-layer capacitance values and intrinsic Rb+ binding constants) were adjusted relatively easily to satisfactorily match the CMD and titration data. The larger hydration energy of Na+ results in a more complex inner-sphere distribution, which shifts from bidentate to tetradentate binding with increasing negative charge and temperature, and this distribution was not matched wel... read less USED (high confidence) D. Zhao, C. Peng, and J. Zhou, “Lipase adsorption on different nanomaterials: a multi-scale simulation study.,” Physical chemistry chemical physics : PCCP. 2015. link Times cited: 61 Abstract: Candida antarctica lipase B (CalB) is an efficient biocataly… read moreAbstract: Candida antarctica lipase B (CalB) is an efficient biocatalyst for hydrolysis and esterification, which plays an important role in the production of biodiesel in the bioenergy industries. The ordered immobilisation of lipases on different supports would be significant for its enzymatic catalysis in some biodiesel production processes; however, the underlying mechanisms and the preferred lipase orientation are not well understood yet. In this work, a fundamental understanding of the orientation and adsorption mechanism of lipase on four different nanomaterial surfaces with different surface chemistry are explored in detail by a combination of parallel tempering Monte Carlo (PTMC) and molecular dynamics (MD) simulations. Simulation results show that lipase is strongly adsorbed onto the hydrophobic graphite surface, as reflected by the large contact area and interaction energy; while the adsorption onto the hydrophilic TiO2 surface is weak due to two strongly adhered water layers; meanwhile lipase undergoes desorption and reorientation processes. For CalB adsorption on positively and negatively charged surfaces (NH2-SAM and COOH-SAM), the orientation distributions of lipase are narrow, and opposite orientations are obtained. CalB adsorbed on NH2-SAM has its catalytic centre oriented towards the surface, which is not conducive to the substrate binding; while the catalytic centre faces toward the solution when it is adsorbed on the COOH-SAM. Besides, the native structures of CalB adsorbed on different surfaces are preserved, which indicates lipase as a robust enzyme. The simulation results will promote our understanding on how surface properties of nanomaterials, such as charge or hydrophobicity, will affect lipase immobilisation, and help us in the rational design and development of immobilised lipase carriers. read less USED (high confidence) G. Mattioli et al., “Interfacial Engineering of P3HT/ZnO Hybrid Solar Cells Using Phthalocyanines: A Joint Theoretical and Experimental Investigation,” Advanced Energy Materials. 2014. link Times cited: 38 Abstract: Atomistic simulations and experimental investigations are co… read moreAbstract: Atomistic simulations and experimental investigations are combined to study heterojunction interfaces of hybrid polymer solar cells, with the aim to better understand and precisely predict their photovoltaic properties. The focus is on a hybrid ternary model system based on a poly(3‐hexylthiophene) (P3HT)/zinc phthalocyanine (ZnPc)/ZnO interface, in which a ZnPc interlayer is applied to improve the performance of the hybrid interface. Theoretical predictions of the ternary system are validated against the properties of a concrete P3HT/ZnPc/ZnO planar heterojunction device. The theoretical predictions closely agree with the photovoltaic properties obtained in P3HT/ZnPc/ZnO solar cells, indicating the strength of the method for modeling hybrid heterojunction interfaces. The theoretical and experimental results reveal that: i) ZnPc molecules in direct contact with a ZnO surface insert new energy levels due to a strong ZnPc/ZnO coupling, ii) electron injection from these new energy levels of ZnPc into ZnO is highly efficient, iii) the ZnPc/ZnO coupling strongly influences the energy levels of the ZnO and P3HT leading to a reduction of the open circuit voltage, and iv) charge carrier recombination at the P3HT/ZnO interface is reduced by the ZnPc interlayer. The intercalation of ZnPc leads to an increase in photocurrent as well as to an overall increase in power conversion. read less USED (high confidence) K. Ghuman and C. V. Singh, “Effect of doping on electronic structure and photocatalytic behavior of amorphous TiO2,” Journal of Physics: Condensed Matter. 2013. link Times cited: 45 Abstract: Visible light photocatalysts based on doped crystalline form… read moreAbstract: Visible light photocatalysts based on doped crystalline forms of titanium dioxide (TiO2) have attracted significant scientific attention in recent decades. Amorphous TiO2, despite many merits over crystalline phases, has not been studied as thoroughly. In this paper, an in-depth analysis of the electronic properties of doped amorphous TiO2 is performed using density functional theory with Hubbard’s energy correction (DFT + U). Monodoping with p-type (N) and n-type (Nb) dopants shows appreciable bandgap reduction, but leads to recombination centers due to the presence of uncompensated charges. To resolve this issue, charge compensation via codoping is attempted. The charge compensated codoping not only reduces the bandgap by 0.4 eV but also eliminates the bandgap states present in monodoped systems responsible for charge carrier recombination. Furthermore, the localized tail states present in the aTiO2 system are eliminated to a large extent which leads to a decrease in the charge recombination and an increase in the charge migration. Thus, appropriate doping of amorphous TiO2 may lead to an alternative route for the development of visible light photocatalysts. read less USED (high confidence) K. Azuma et al., “Scanning Tunneling Microscopy and Molecular Dynamics Study of the Li2TiO3(001) Surface,” Journal of Physical Chemistry C. 2013. link Times cited: 21 Abstract: We have investigated the (001) surface structure of lithium … read moreAbstract: We have investigated the (001) surface structure of lithium titanate (Li2TiO3) using auger electron spectroscopy (AES), low-energy electron diffraction (LEED), and scanning tunneling microscopy (STM). Li2TiO3 is a potential fusion reactor blanket material. After annealing at 1200 K, LEED demonstrated that the Li2TiO3(001) surface was well ordered and not reconstructed. STM imaging showed that terraces are separated in height by about 0.3 nm suggesting a single termination layer. Moreover, hexagonal patterns with a periodicity of ∼0.4 nm are observed. On the basis of molecular dynamics (MD) simulations, these are interpreted as a dynamic arrangement of Li atoms. read less USED (high confidence) E. Canesi et al., “The effect of selective interactions at the interface of polymer–oxide hybrid solar cells,” Energy and Environmental Science. 2012. link Times cited: 45 Abstract: The working mechanisms of excitonic solar cells are strongly… read moreAbstract: The working mechanisms of excitonic solar cells are strongly dominated by interface processes, which influence the final device efficiency. However, it is still very challenging to clearly track the effects of inter-molecular processes at a mesoscopic level. We report on the realization of polymer-based hybrid solar cells made of prototypical materials, namely, poly(3-hexylthiophene) (P3HT) finely infiltrated in a TiO2 scaffold, with power conversion efficiency exceeding 1%. A step-change improvement in the device performance is enabled by engineering the hybrid interface by the insertion of an appropriate molecular interlayer. An unprecedented set of characterization techniques, including time-resolved optical spectroscopy, X-ray photoemission spectroscopy, positron annihilation spectroscopy and atomistic simulations, allows us to rationalize our findings. We show that a suitable chemical structure of the interlayer molecule induces selective intermolecular interactions, and thus a preferential surface energetic landscape and morphological order at the interface which consequently drives a strong improvement in charge generation and a decrease in recombination losses. read less USED (high confidence) E. Dushanov, K. Kholmurodov, and K. Yasuoka, “Molecular dynamics studies of the interaction between water and oxide surfaces,” Physics of Particles and Nuclei Letters. 2012. link Times cited: 11 USED (high confidence) S. Salameh et al., “Adhesion mechanisms of the contact interface of TiO2 nanoparticles in films and aggregates.,” Langmuir : the ACS journal of surfaces and colloids. 2012. link Times cited: 76 Abstract: Fundamental knowledge about the mechanisms of adhesion betwe… read moreAbstract: Fundamental knowledge about the mechanisms of adhesion between oxide particles with diameters of few nanometers is impeded by the difficulties associated with direct measurements of contact forces at such a small size scale. Here we develop a strategy based on AFM force spectroscopy combined with all-atom molecular dynamics simulations to quantify and explain the nature of the contact forces between 10 nm small TiO(2) nanoparticles. The method is based on the statistical analysis of the force peaks measured in repeated approaching/retracting loops of an AFM cantilever into a film of nanoparticle agglomerates and relies on the in-situ imaging of the film stretching behavior in an AFM/TEM setup. Sliding and rolling events first lead to local rearrangements in the film structure when subjected to tensile load, prior to its final rupture caused by the reversible detaching of individual nanoparticles. The associated contact force of about 2.5 nN is in quantitative agreement with the results of molecular dynamics simulations of the particle-particle detachment. We reveal that the contact forces are dominated by the structure of water layers adsorbed on the particles' surfaces at ambient conditions. This leads to nonmonotonous force-displacement curves that can be explained only in part by classical capillary effects and highlights the importance of considering explicitly the molecular nature of the adsorbates. read less USED (high confidence) G. Mattioli et al., “Zinc Oxide-Zinc Phthalocyanine interface for Hybrid Solar Cells,” Journal of Physical Chemistry C. 2012. link Times cited: 37 Abstract: The structural, electronic, and optical properties of a hybr… read moreAbstract: The structural, electronic, and optical properties of a hybrid interface formed by zinc phthalocyanine (ZnPc) molecules adsorbed on the (1010) zinc oxide (ZnO) surface have been investigated by using ab initio and model potential theoretical methods. In particular, the attention has been focused on the effects of molecular assembling on the interface properties by considering cofacial and planar molecular aggregates on the surface. Present results show that planar aggregations provide a remarkable molecule-to-surface electronic coupling which can favor electron injection toward the substrate. Furthermore, we predict a blue shift of absorption bands in the case of cofacial aggregation and a red shift in the case of nanostructured planar J-stripes, which are in agreement with previous phenomenological models and give a firm theoretical support to observed relationships between red shift and molecular assembling. All together, present results indicate that structural and electronic properties can be achieve... read less USED (high confidence) M. Saba, V. Calzia, C. Melis, L. Colombo, and A. Mattoni, “Atomistic Investigation of the Solid–Liquid Interface between the Crystalline Zinc Oxide Surface and the Liquid Tetrahydrofuran Solvent,” Journal of Physical Chemistry C. 2012. link Times cited: 7 Abstract: Zinc oxide is typically used as an electron acceptor in the … read moreAbstract: Zinc oxide is typically used as an electron acceptor in the preparation of hybrid solar cells. Such hybrids are, in many cases, synthesized from solutions. In this work, we investigate the possible persistence of solvent tetrahydrofuran molecules at the interface with zinc oxide by means of atomistic simulations based on model potentials and density functional theory calculations. We found a strong interaction between the solvent and the zinc oxide that leads to the formation of an ordered layer of tetrahydrofuran molecules bound to the zinc oxide substrate. read less USED (high confidence) X. Bai and B. Uberuaga, “Multi-timescale investigation of radiation damage near TiO2 rutile grain boundaries,” Philosophical Magazine. 2012. link Times cited: 31 Abstract: To understand the interactions between defects and grain bou… read moreAbstract: To understand the interactions between defects and grain boundaries (GBs) in oxides, two atomistic modeling methods were used to examine the role of GBs in a model system, rutile TiO2, in modifying radiation-induced defect production and annealing. Molecular dynamics was used to investigate defect production near a symmetric tilt GB at both 300 K and 1000 K. The damage production is found to be sensitive to the initial distance of the primary knock-on atom from the GB. We find three distinct regimes in which GBs have different effects. Similar to GBs in metals, the GB absorbs more interstitials than vacancies at certain distances while this behavior of biased loading of interstitials diminishes at other distances. Further, we obtain the statistics of both interstitial and vacancy clusters produced in collision cascades in terms of their compositions at two temperatures. Perfectly stoichiometric defect clusters represent a small fraction of the total clusters produced. Moreover, a significant reduction in the number of interstitial clusters at 1000 K compared to 300 K is thought to be a consequence of enhanced migration of interstitials towards the GB. Finally, the kinetic properties of certain defect clusters were investigated with temperature accelerated dynamics, without any a priori assumptions of migration mechanisms. Small interstitial clusters become mobile at high temperatures while small vacancy clusters do not. Multiple migration pathways exist and are typically complex and non-intuitive. We use this kinetic information to explain experimental observations and predict their long-time migration behavior near GBs. read less USED (high confidence) C. Melis, P. Raiteri, L. Colombo, and A. Mattoni, “Self-assembling of zinc phthalocyanines on ZnO (1010) surface through multiple time scales.,” ACS nano. 2011. link Times cited: 14 Abstract: We adopt a hierarchic combination of theoretical methods to … read moreAbstract: We adopt a hierarchic combination of theoretical methods to study the assembling of zinc phthalocyanines (ZnPcs) on a ZnO (1010) surface through multiple time scales. Atomistic simulations, such as model potential molecular dynamics and metadynamics, are used to study the energetics and short time evolution (up to ∼100 ns) of small ZnPc aggregates. The stability and the lifetime of large clusters is then studied by means of an atomistically informed coarse-grained model using classical molecular dynamics. Finally, the macroscopic time scale clustering phenomenon is studied by Metropolis Monte Carlo algorithms as a function of temperature and surface coverage. We provide evidence that at room temperature the aggregation is likely to occur at sufficiently high coverage, and we characterize the nature, morphology, and lifetime of ZnPc's clusters. We identify the molecular stripes oriented along [010] crystallographic directions as the most energetically stable aggregates. read less USED (high confidence) S. J. Konezny et al., “Fluctuation-Induced Tunneling Conductivity in Nanoporous TiO2 Thin Films,” Journal of Physical Chemistry Letters. 2011. link Times cited: 17 Abstract: The electronic mechanisms responsible for dark conductivity … read moreAbstract: The electronic mechanisms responsible for dark conductivity in nanoporous TiO2 thin films remain only partially understood, although they control the efficiency of charge transport in a wide range of technological applications. Measurements in the 78–335 K temperature range show DC conductivity values spanning over 4 orders of magnitude, with a high-temperature Arrhenius dependence that gradually changes into a temperature-independent plateau at low temperatures. We show evidence that a fluctuation-induced tunneling conductivity (FITC) mechanism is fully consistent with the experimental data. Quantitative agreement is demonstrated for the entire temperature range (T = 78–335 K) with a FITC model parametrized according to atomistic models of nanoporous TiO2 and the characterization of the films by X-ray diffraction and scanning electron microscopy measurements. These findings suggest that dark DC conductivity in nanoporous TiO2 films depends strongly on the properties of the junctions linking the constitue... read less USED (high confidence) L. Dai, C. Sow, C. T. Lim, and V. Tan, “Metal Oxide Nanowires – Structural and Mechanical Properties.” 2011. link Times cited: 2 Abstract: Metal Oxide nanowires are versatile nanostructured materials… read moreAbstract: Metal Oxide nanowires are versatile nanostructured materials with diverse yet unique properties. Potentially, they have a wide range of applications in electrical, chemical and semiconductor technologies (Yang, Wu et al. 2002; Rao, Deepak et al. 2003; Law, Goldberger et al. 2004; Shankar and Raychaudhuri 2005; Lu, Chang et al. 2006; Lu and Lieber 2006). Research interests in metal oxide nanowires commenced in 1990s. Up to now, there have been a considerable number of reports on success in the synthesis of 1-dimensional nanocrystalline structured nanowires of various metal oxides, such as CuO(Wang, Zhan et al. 2001; Jiang, Herricks et al. 2002), MgO(Ma and Bando 2003), ZnO(Tian, Voigt et al. 2003; Vayssieres 2003; Heo, Norton et al. 2004; Wang, Song et al. 2007; Manoharan, Desai et al. 2008), TiO2(Lakshmi, Partissi et al. 1997; Li and Wang 1999; Li and Xia 2003; Wu, Shih et al. 2005; Wu, Shih et al. 2006), Al2O3(Valcarcel, Souto et al. 1998; Xiao, Han et al. 2002), Ga2O3(Wu, Song et al. 2000), In2O3(Li, Zhang et al. 2003), SnO2(Dai, Pan et al. 2001), Sb2O5(Guo, Wu et al. 2000), V2O5(Chen, Sun et al. 2002), BaTiO3(Urban, Spanier et al. 2003), etc. The methodology of synthesis is now well developed. Reported techniques include vapor-solid phase technique(Valcarcel, Souto et al. 1998; Wu, Song et al. 2000; Jiang, Herricks et al. 2002; Ma and Bando 2003; Wu, Shih et al. 2005; Wu, Shih et al. 2006), chemical solution deposition (sol-gel) (Lakshmi, Partissi et al. 1997; Urban, Spanier et al. 2003), template etching(Xiao, Han et al. 2002), percipitation(Tian, Voigt et al. 2003; Vayssieres 2003), micro-emulsion(Guo, Wu et al. 2000), flux growth(Dai, Pan et al. 2001) and others. These are well reviewed by Shangkar et al.(Shankar and Raychaudhuri 2005). Among all the properties of metal oxide nanowires, their mechanical property is one of the most highly structure dependent and features strongly in many applications. The structural and mechanical phenomena and related mechanisms have attracted significant research interests. However, due to the difficulties in manipulating the nano-sized specimens, experimental characterizations are limited to simple mechanical tests to measure quantities like Young’s modulus, strength et al. Comparatively, numerical studies, especially molecular dynamics (MD) simulations, are well suited for nanostructured materials, and have been broadly applied for investigating structural and mechanical properties. In this chapter, we will review the structural characteristics and mechanical properties of different types of metal oxides, both experimentally and numerically. Besides reviewing published literatures, we will be focusing on reporting the outputs from our research group. read less USED (high confidence) D. Song, M. Chen, Y. Liang, Q. Bai, J. Chen, and X. Zheng, “Adsorption of tripeptide RGD on rutile TiO(2) nanotopography surface in aqueous solution.,” Acta biomaterialia. 2010. link Times cited: 48 USED (high confidence) E. Sanville et al., “Surface and interstitial transition barriers in rutile (110) surface growth,” Physical Review B. 2009. link Times cited: 17 Abstract: We present calculated surface and interstitial transition ba… read moreAbstract: We present calculated surface and interstitial transition barriers for Ti, O, O-2, TiO, and TiO2 atoms and clusters at the rutile (110) surface. Defect structures involving these small clusters, including adcluster and interstitial binding sites, were calculated by energy minimization using density-functional theory (DFT). Transition energies between these defect sites were calculated using the NEB method. Additionally, a modified SMB-Q charge equilibration empirical potential and a fixed-charge empirical potential were used for a comparison of the transition energy barriers. Barriers of 1.2-3.5 eV were found for all studied small cluster transitions upon the surface except for transitions involving O-2. By contrast, the O-2 diffusion barriers along the [001] direction upon the surface are only 0.13 eV. The QEq charge equilibration model gave mixed agreement with the DFT calculations, with the barriers ranging between 0.8 and 5.8 eV. read less USED (high confidence) Y. Liang, D. Song, M. Chen, and Q. Bai, “Adsorption mechanism of arg-gly-asp on rutile TiO2 (110) surface in aqueous solution,” Journal of Vacuum Science & Technology B. 2009. link Times cited: 2 Abstract: Molecular dynamics simulations were performed to investigate… read moreAbstract: Molecular dynamics simulations were performed to investigate the adsorption mechanism of arg-gly-asp (RGD) tripeptide on pit and perfect rutile TiO2 (110) surfaces in aqueous solution and the competitive mechanism of RGD and water. It is shown that the adsorption of RGD on pit surface is more stable than that on perfect surface, and the adsorption energy of the pit surface is −106.14 kcal mol−1, which is 1.8 times as big as that of the perfect surface. Water influences significantly RGD adsorption on the surface. The water molecules reach first the surface and occupy the adsorption sites, i.e., the water oxygen atoms bond to the surface fivefold titanium atoms to form the stable first hydration layer and interact with the surface bridging oxygen atoms to form the second hydration layer. The subsequent arrival RGD edges out the adsorbed water molecules bonding to the surface oxygen atoms and forms hydrogen bonds with these oxygen atoms. Electrostatic and van der Waals interactions are the main interactions... read less USED (high confidence) B. Chen et al., “Size-dependent elasticity of nanocrystalline titania,” Physical Review B. 2009. link Times cited: 55 Abstract: Synchrotron-based high-pressure x-ray diffraction measuremen… read moreAbstract: Synchrotron-based high-pressure x-ray diffraction measurements indicate that compressibility, a fundamental materials property, can have a size-specific minimum value. The bulk modulus of nanocrystalline titania has a maximum at particle size of 15 nm. This can be explained by dislocation behavior because very high dislocation contents can be achieved when shear stress induced within nanoparticles counters the repulsion between dislocations. As particle size decreases, compression increasingly generates dislocation networks hardened by overlap of strain fields that shield intervening regions from external pressure. However, when particles become too small to sustain high dislocation concentrations, elastic stiffening declines. The compressibility has a minimum at intermediate sizes. read less USED (high confidence) V. Kopardé and P. Cummings, “Sintering of titanium dioxide nanoparticles: a comparison between molecular dynamics and phenomenological modeling,” Journal of Nanoparticle Research. 2008. link Times cited: 58 USED (high confidence) V. V. Hoang, “Pressure-induced structural transition in amorphous TiO2 nanoparticles and in the bulk via molecular dynamics simulation,” Journal of Physics D: Applied Physics. 2007. link Times cited: 24 Abstract: The pressure-induced structural transition in amorphous TiO2… read moreAbstract: The pressure-induced structural transition in amorphous TiO2 nanoparticles has been studied in a spherical model of different diameters of 2, 3 and 4 nm under non-periodic boundary conditions. We use the pairwise interatomic potentials proposed by Matsui and Akaogi. Models have been compressed from 3.8 g cm−3 up to very high density (i.e. high pressure) in order to investigate the pressure-induced structural changes. We found the change from the low-density amorphous (lda) form with ZTi–O ≈ 6.0 to the high-density amorphous (hda) one with ZTi–O ≈ 7.0 to be like those observed in practice. We found that the transition pressure is nanoparticle size dependent due to the surface effects. In order to compare and highlight the features of such transition in nanoparticles, we also present the results for the same transition in the amorphous TiO2 models containing 3000 atoms under periodic boundary conditions, which could be considered as bulk counterparts. Structural properties of nanoparticles at 700 K have been analysed in detail through the partial radial distribution functions, interatomic distances, coordination number and bond-angle distributions. Moreover, we also show the radial density profile in nanoparticles. read less USED (high confidence) A. Foster et al., “Towards chemical identification in atomic-resolution noncontact afm imaging with silicon tips,” Physical Review B. 2003. link Times cited: 87 Abstract: In this study we use ab initio calculations and a pure silic… read moreAbstract: In this study we use ab initio calculations and a pure silicon tip to study the tip-surface interaction with four characteristic insulating surfaces: (i) the narrow gap TiO2 (110) surface, (ii) the classic oxide MgO (001) surface, (iii) the ionic solid CaCO3 (10(1) over bar4) surface with molecular anion, and (iv) the wide gap CaF2 (111) surface. Generally we find that the tip-surface interaction strongly depends on the surface electronic structure due to the dominance of covalent bond formation with the silicon tip. However, we also find that in every case the strongest interaction is with the highest anion of the surface. This result suggests that, if the original silicon tip can be carefully controlled, it should be possible to immediately identify the species seen as bright in images of insulating surfaces. In order to provide a more complete picture we also compare these results to those for contaminated tips and suggest how applied voltage could also be used to probe chemical identity. read less USED (high confidence) A. Foster, O. Pakarinen, J. Airaksinen, J. Gale, and R. Nieminen, “Simulating atomic force microscopy imaging of the ideal and defected TiO2 (110) surface,” Physical Review B. 2003. link Times cited: 17 Abstract: In this study we simulate noncontact atomic force microscopy… read moreAbstract: In this study we simulate noncontact atomic force microscopy imaging of the TiO 2 (110) surface using first-principles and atomistic methods. We use three different tip models to investigate the tip-surface interaction onthe ideal surface, and find that agreement with experiment is found for either a silicon tip or a tip with a net positive electrostatic potential from the apex. Both predict bright contrast over the bridging oxygen rows. We then study the interaction of this tip with a bridging oxygen vacancy on the surface, and find that the much weaker interaction observed would result in vacancies appearing as dark contrast along the bright rows in images. read less USED (high confidence) M. Jongmanns and D. Wolf, “Element‐specific displacements in defect‐enriched TiO
2
: Indication of a flash sintering mechanism,” Journal of the American Ceramic Society. 2019. link Times cited: 29 USED (high confidence) K. Kaur and C. V. Singh, “Amorphous TiO2 as a Photocatalyst for Hydrogen Production: A DFT Study of Structural and Electronic Properties,” Energy Procedia. 2012. link Times cited: 95 USED (high confidence) J. Wang, S. Li, W. Yan, S. Tse, and Q. Yao, “Synthesis of TiO2 nanoparticles by premixed stagnation swirl flames.” 2011. link Times cited: 60 USED (low confidence) G. Tatrari, M. Ahmed, and F. U. Shah, “Synthesis, thermoelectric and energy storage performance of transition metal oxides composites,” Coordination Chemistry Reviews. 2024. link Times cited: 0 USED (low confidence) L. Zhou, L. He, D. Yang, and Y. Li, “He atoms diffusion and aggregation in Li2TiO3: A molecular dynamics study,” Nuclear Engineering and Design. 2023. link Times cited: 0 USED (low confidence) E. P. E. Ruiz, S. Thirumuruganandham, and J. C. L. Lago, “Structural and Electromagnetic Signatures of Anatase and Rutile NTs and Sheets in Three Different Water Models under Different Temperature Conditions,” International Journal of Molecular Sciences. 2023. link Times cited: 0 Abstract: Experimental studies of TiO2 nanotubes have been conducted f… read moreAbstract: Experimental studies of TiO2 nanotubes have been conducted for nearly three decades and have revealed the remarkable advantages of this material. Research based on computer simulations is much rarer, with research using density functional theory (DFT) being the most significant in this field. It should be noted, however, that this approach has significant limitations when studying the macroscopic properties of nanostructures such as nanosheets and nanotubes. An alternative with great potential has emerged: classical molecular dynamics simulations (MD). MD Simulations offer the possibility to study macroscopic properties such as the density of phonon states (PDOS), power spectra, infrared spectrum, water absorption and others. From this point of view, the present study focuses on the distinction between the phases of anatase and rutile TiO2. The LAMMPS package is used to study both the structural properties by applying the radial distribution function (RDF) and the electromagnetic properties of these phases. Our efforts are focused on exploring the effect of temperature on the vibrational properties of TiO2 anatase nanotubes and an in-depth analysis of how the phononic softening phenomenon affects TiO2 nanostructures to improve the fundamental understanding in different dimensions and morphological configurations. A careful evaluation of the stability of TiO2 nanolamines and nanotubes at different temperatures is performed, as well as the adsorption of water on the nanosurface of TiO2, using three different water models. read less USED (low confidence) S. Zhang and Y. Wu, “Investigating the crystallization behavior of TiO2 during annealing: Molecular dynamics simulations,” AIP Advances. 2023. link Times cited: 0 Abstract: TiO2 is a dielectric material with excellent photocatalytic … read moreAbstract: TiO2 is a dielectric material with excellent photocatalytic and photochemical properties. The conversion of TiO2 from an amorphous to crystalline phase significantly improves the photocatalytic activity of TiO2. However, the crystallization behavior of TiO2 during annealing has been little studied in the field of molecular dynamics. In this paper, the crystallization behavior of TiO2 during annealing under different conditions was analyzed using molecular dynamics simulation. To investigate the phase transition process of TiO2, the melting point temperature of the system was calculated by mean square displacement at about 2400 K. The effect of size on structural stability was explored. The radial distribution function and x-ray diffraction curves revealed that the anatase phase appeared over 800 K. Moreover, with the increase in annealing temperature, the anatase content in TiO2 first increased and then decreased, and the rutile phase gradually increased. At a specific temperature, a structure is formed where rutile and anatase coexist. Anatase atoms compete with rutile atoms, and by increasing the temperature, anatase is converted to rutile. The amorphous structure is reduced at high temperatures, improving the crystalline quality. The crystallization behavior of the amorphous structure can improve the photocatalytic efficiency of TiO2. TiO2 nanometers have good prospect for application. Therefore, studying the crystallization behavior of TiO2 is essential. read less USED (low confidence) D. O’Carroll and N. J. English, “Multi-Theory Comparisons of Molecular Simulation Approaches to TiO2/H2O Interfacial Systems,” Crystals. 2023. link Times cited: 0 Abstract: Herein, we present molecular dynamics analyses of systems co… read moreAbstract: Herein, we present molecular dynamics analyses of systems containing TiO2 interfaces with water, simulated using empirical forcefields (FF), Density-Functional Tight-Binding (DFTB), and Density-Functional Theory (DFT) methodologies. The results and observed differences between the methodologies are discussed, with the aim of assessing the suitability of each methodology for performing molecular dynamics simulations of catalytic systems. Generally, well-parameterised forcefield MD outperforms the other methodologies—albeit, at the expense of neglecting certain qualitative behaviours entirely. DFTB represents an attractive compromise method, and has the potential to revolutionise the field of molecular dynamics in the near future due to advances in generating parameters. read less USED (low confidence) Q. Mao, M. Feng, X. Jiang, Y. Ren, K. Luo, and A. V. van Duin, “Classical and reactive molecular dynamics: Principles and applications in combustion and energy systems,” Progress in Energy and Combustion Science. 2023. link Times cited: 10 USED (low confidence) G. M. Repa and L. A. Fredin, “Predicting Electronic Structure of Realistic Amorphous Surfaces,” Advanced Theory and Simulations. 2023. link Times cited: 0 Abstract: Amorphous materials underlie the functionality of many devic… read moreAbstract: Amorphous materials underlie the functionality of many devices in photocatalysis, electronics, and other technological applications. The performance of such devices is largely altered by the interfacial characteristics of the material motivating better understanding of their structure function relationships. However, open questions remain about how to generate atomistic representations of amorphous surfaces that are realistic while being amenable to computational study using electronic structure methods. Here, model parameters are explored to generate accurate amorphous surface models using prototypical amorphous titanium dioxide and a melt‐quench approach. In particular, non‐standard model considerations such as minimum sample size, unit cell size, and quench conditions are varied to efficiently explore amorphous structural space. The results indicate different modeling parameters have a substantial effect on surface morphology and electronic structure that significantly alters the interpretations gained by computational study of amorphous interfaces. Critically, it is shown that the structural motifs that contribute to such differences are not detectable by short range structural analysis that has traditionally been used to assess the quality of melt‐quench derived amorphous structures. read less USED (low confidence) F. Grigoriev and V. Sulimov, “Atomistic Simulation of Physical Vapor Deposition of Optical Thin Films,” Nanomaterials. 2023. link Times cited: 0 Abstract: A review of the methods and results of atomistic modeling of… read moreAbstract: A review of the methods and results of atomistic modeling of the deposition of thin optical films and a calculation of their characteristics is presented. The simulation of various processes in a vacuum chamber, including target sputtering and the formation of film layers, is considered. Methods for calculating the structural, mechanical, optical, and electronic properties of thin optical films and film-forming materials are discussed. The application of these methods to studying the dependences of the characteristics of thin optical films on the main deposition parameters is considered. The simulation results are compared with experimental data. read less USED (low confidence) Y. Dong et al., “Substantial lifetime enhancement for Si-based photoanodes enabled by amorphous TiO2 coating with improved stoichiometry,” Nature Communications. 2023. link Times cited: 3 USED (low confidence) A. Kuzminova et al., “Novel Mixed Matrix Membranes Based on Poly(vinylidene fluoride): Development, Characterization, Modeling,” Polymers. 2023. link Times cited: 2 Abstract: Membrane technology is an actively developing area of modern… read moreAbstract: Membrane technology is an actively developing area of modern societies; with the help of high-performance membranes, it is possible to separate various mixtures for many industrial tasks. The objective of this study was to develop novel effective membranes based on poly(vinylidene fluoride) (PVDF) by its modification with various nanoparticles (TiO2, Ag-TiO2, GO-TiO2, and MWCNT/TiO2). Two types of membranes have been developed: dense membranes for pervaporation and porous membranes for ultrafiltration. The optimal content of nanoparticles in the PVDF matrix was selected: 0.3 wt% for porous membranes and 0.5 wt% for dense ones. The structural and physicochemical properties of the developed membranes were studied using FTIR spectroscopy, thermogravimetric analysis, scanning electron and atomic force microscopies, and measuring of contact angles. In addition, the molecular dynamics simulation of PVDF and the TiO2 system was applied. The transport properties and cleaning ability under ultraviolet irradiation of porous membranes were studied by ultrafiltration of a bovine serum albumin solution. The transport properties of dense membranes were tested in pervaporation separation of a water/isopropanol mixture. It was found that membranes with the optimal transport properties are as follows: the dense membrane modified with 0.5 wt% GO-TiO2 and the porous membrane modified with 0.3 wt% MWCNT/TiO2 and Ag-TiO2. read less USED (low confidence) N. Sheveleva, A. Komolkin, and D. Markelov, “Influence of the Chemical Structure on the Mechanical Relaxation of Dendrimers,” Polymers. 2023. link Times cited: 0 Abstract: The rheological properties of macromolecules represent one o… read moreAbstract: The rheological properties of macromolecules represent one of the fundamental features of polymer systems which expand the possibilities of using and developing new materials based on them. In this work, we studied the shear-stress relaxation of the second generation PAMAM and PPI dendrimer melts by atomistic molecular dynamics simulation. The time dependences of relaxation modulus G(t) and the frequency dependences of the storage G′(ω) and loss G″(ω) moduli were obtained. The results were compared with the similar dependences for the polycarbosilane (PCS) dendrimer of the same generation. The chemical structure of the dendrimer segments has been found to strongly influence their mechanical relaxation. In particular, it has been shown that hydrogen bonding in PAMAM dendrimers leads to an entanglement of macromolecules and the region is observed where G′(ω) > G″(ω). This slows down the mechanical relaxation and rotational diffusion of macromolecules. We believe that our comprehensive research contributes to the systematization of knowledge about the rheological properties of dendrimers. read less USED (low confidence) O. Berger, “Understanding the fundamentals of TiO2 surfacesPart II. Reactivity and surface chemistry of TiO2 single crystals,” Surface Engineering. 2022. link Times cited: 0 Abstract: ABSTRACT In order to promote the application of TiO2 in surf… read moreAbstract: ABSTRACT In order to promote the application of TiO2 in surface modification technologies, a detailed understanding of its structure and properties is necessary. For this reason, the reactivity and corresponding surface chemistry of stoichiometric and non-stoichiometric single crystals of titanium dioxide have been widely studied. In Part II of this review, special attention is paid to the role of individual surface sites and the effect of available charge on the adsorption processes on stoichiometric and reduced single crystal rutile and anatase surfaces. In addition, the most appropriate surface science methods used to study the surface chemistry of these surfaces are also highlighted. An understanding of the interaction of H2O and O2 with oxide surfaces is extremely important because these adsorbates form a de facto part of the environment in all technological applications. Moreover, they play an extraordinarily important role in the processes taking place in high-performance devices in the fields of energy, environment, and health. Consequently, special consideration is given to the adsorption and dissociation processes of the most technologically important inorganic adsorbates, such as H2O and O2, on model low Miller index single crystal surfaces of titania. In addition, light-induced reactivity of TiO2 and its application is also considered. Furthermore, the engineering of TiO2 nanocrystals with well-defined facets, their unusual photocatalytic properties, and applications are also briefly considered. read less USED (low confidence) G. M. Repa and L. A. Fredin, “Capturing experimental properties in computationally efficient faceted titania nanoparticle models,” International Journal of Quantum Chemistry. 2022. link Times cited: 1 Abstract: Understanding the surface chemistry of nanostructured TiO2 h… read moreAbstract: Understanding the surface chemistry of nanostructured TiO2 has long been a priority to improve photochemical device efficiency. Faceted nanoparticles, characterized by known facets not at thermodynamically ideal ratios, are particularly challenging to model due to the large number of chemical and computational parameters that must be chosen for which there is no experimental guidance. This research supplies a modeling framework for faceted TiO2 nanoparticles that provides rationale for such decisions. By performing full DFT optimization and characterization on a series of inter-related anatase TiO2 nanoparticles displaying {101}, (001), and {010} facets with sizes up to 202 TiO2 units, parameter space is mapped with regard to particle size, shape, defects, and optimization protocol. Specifically, it is shown that pre-optimization is necessary in order to achieve a sufficiently delocalized electronic structure, and the increased reorganization afforded by removing higher coordinated Ti atoms compensates the high formation energy of creating these defects. Furthermore, by characterizing differently shaped nanoparticles with the same number of TiO2 units, this research provides direct observation of shape effects on nanoparticles. read less USED (low confidence) R. J. Cordina, B. Smith, and T. Tuttle, “Rapid Automated Quantification of Triacylglyceride Crystallinity in Molecular Dynamics Simulations,” Journal of Chemical Information and Modeling. 2022. link Times cited: 1 Abstract: The relative stability of crystalline polymorphs and the tra… read moreAbstract: The relative stability of crystalline polymorphs and the transition between crystalline and melt phases are key parameters in determining the physical properties of triacylglycerides used in food. However, while the determination of properties experimentally is well-defined, the ability to predict the onset of melting and discriminate between polymorphs is less well-defined within a molecular dynamics simulation environment. In this work, we present metrics for measuring the crystallinity, including a new metric, the near-neighbor occupancy time, giving a rapid determination of how many, and which, molecules are found in a crystal over a simulation trajectory, and the polymorphic determination of triacylglycerides over a simulation trajectory. read less USED (low confidence) R. Rymzhanov, A. Akzhunussov, A. Volkov, A. Ibrayeva, and V. Skuratov, “Thermal conductivity of Al2O3 irradiated with swift heavy ions,” Nuclear Materials and Energy. 2022. link Times cited: 1 USED (low confidence) S. Homann, H. Luu, and N. M. (née Gunkelmann), “Molecular dynamics simulations of the machining of oxidized and deoxidized titanium work pieces,” Results in Surfaces and Interfaces. 2022. link Times cited: 0 USED (low confidence) F. Grigoriev, V. Sulimov, and A. Tikhonravov, “Atomistic Simulation of the Ion-Assisted Deposition of Silicon Dioxide Thin Films,” Nanomaterials. 2022. link Times cited: 2 Abstract: A systematic study of the most significant parameters of the… read moreAbstract: A systematic study of the most significant parameters of the ion-assisted deposited silicon dioxide films is carried out using the classical molecular dynamics method. The energy of the deposited silicon and oxygen atoms corresponds to the thermal evaporation of the target; the energy of the assisting oxygen ions is 100 eV. It is found that an increase in the flow of assisting ions to approximately 10% of the flow of deposited atoms leads to an increase in density and refractive index by 0.5 g/cm3 and 0.1, respectively. A further increase in the flux of assisting ions slightly affects the film density and density profile. The concentration of point defects, which affect the optical properties of the films, and stressed structural rings with two or three silicon atoms noticeably decrease with an increase in the flux of assisting ions. The film growth rate somewhat decreases with an increase in the assisting ions flux. The dependence of the surface roughness on the assisting ions flux is investigated. The anisotropy of the deposited films, due to the difference in the directions of motion of the deposited atoms and assisting ions, is estimated using the effective medium approach. read less USED (low confidence) A. Sorkin, Y. Guo, M. Ihara, S. Manzhos, and H. Wang, “Non-invasive improvement of machining by reversible electrochemical doping: A proof of principle with computational modeling on the example of lithiation of TiO2,” Materials Chemistry and Physics. 2022. link Times cited: 3 USED (low confidence) M. C. Masedi and P. Ngoepe, “Multi-scale simulations and phase stability prediction of mixed Li2S1-xSex system,” Journal of Physics: Conference Series. 2022. link Times cited: 0 Abstract: Lithium-sulfur (Li-S) batteries are a popular Li-ion alterna… read moreAbstract: Lithium-sulfur (Li-S) batteries are a popular Li-ion alternative because they have a high capacity (1672 mAhg1) and energy density (2500 Wh kg1) while being inexpensive, environmentally friendly, and lightweight [1–3]. During cycling, Li/S is hampered by the low conductivity of S and the solubility of intermediary polysulfide species. Se and mixed SexSy have been shown to offer an appealing new class of cathode materials with good electrochemical performance in both Li and Na ion processes [4]. These new Se and Li/SexSy electrodes can cycle at ambient temperature, unlike existing Li/S batteries, which can only operate at high temperatures. Room temperature cycling is possible using Li/SexSy electrodes. Empirical interatomic potentials of Li2S were generated and confirmed against existing experimental and predicted structure, elastic properties, and phonon spectra in order to analyse large systems and the impact of temperature effectively. Complex high-temperature changes including Li2S melting were also replicated, as predicted by molecular dynamics simulations. read less USED (low confidence) T. Ji et al., “Intense Microwave Heating at Strongly Polarized Solid Acid/water Interface for Energy-efficient Platform Chemical Production,” Chemical Engineering Science. 2022. link Times cited: 2 USED (low confidence) Y. Li, B. Wang, M. Cui, X. Li, and M. Li, “Methyl passivation is better than silicon oxide passivation in five aspects for the Si/PEDOT:PSS interface,” Applied Surface Science. 2022. link Times cited: 1 USED (low confidence) T. Dikici et al., “Production of Zn-doped TiO2 film with enhanced photocatalytic activity,” Journal of the Australian Ceramic Society. 2022. link Times cited: 5 USED (low confidence) S. J. Boyd, D. O’Carroll, Y. Krishnan, R. Long, and N. J. English, “Self-Diffusion of Individual Adsorbed Water Molecules at Rutile (110) and Anatase (101) TiO2 Interfaces from Molecular Dynamics,” Crystals. 2022. link Times cited: 0 Abstract: The distribution of individual water molecules’ self-diffusi… read moreAbstract: The distribution of individual water molecules’ self-diffusivities in adsorbed layers at TiO2 surfaces anatase (101) and rutile (110) have been determined at 300 K for inner and outer adsorbed layers, via classical molecular-dynamics methods. The layered-water structure has been identified and classified in layers making use of local order parameters, which proved to be an equally valid method of “self-ordering” molecules in layers. Significant distinctness was observed between anatase and rutile in disturbing these molecular distributions, more specifically in the adsorbed outer layer. Anatase (101) presented significantly higher values of self-diffusivity, presumably due to its “corrugated” structure that allows more hydrogen bonding interaction with adsorbed molecules beyond the first hydration layer. On the contrary, rutile (110) has adsorbed water molecules more securely “trapped” in the region between Ob atoms, resulting in less mobile adsorbed layers. read less USED (low confidence) A. Holm, A. Kupferer, S. Mändl, A. Lotnyk, and S. G. Mayr, “Conductive Tracks in Carbon Implanted Titania Nanotubes: Atomic‐Scale Insights from Experimentally Based Ab Initio Molecular Dynamics Modeling,” Advanced Theory and Simulations. 2022. link Times cited: 1 Abstract: Ion implantation of titania nanotubes is a highly versatile … read moreAbstract: Ion implantation of titania nanotubes is a highly versatile approach for tailoring structural and electrical properties. While recently self‐organized nanoscale compositional patterning has been reported, the atomistic foundations and impact on electronic structure are not established at this point. To study these aspects, ab initio molecular dynamic simulations based on atomic compositions in C implanted titania nanotubes according to elastic recoil detection analysis are employed. Consistent with experimental data, carbon accumulates in chainlike precipitates, which are favorable for enhancing conductivity, as revealed by density‐functional theory electronic ground states calculations are demonstrated. read less USED (low confidence) D. Sahoo, P. Chaudhuri, and N. Swaminathan, “Primary radiation damages in Li2TiO3 and Li4SiO4: a comparison study using molecular dynamics simulation,” Radiation Effects and Defects in Solids. 2022. link Times cited: 1 Abstract: Molecular dynamics simulations are conducted on β-Li TiO and… read moreAbstract: Molecular dynamics simulations are conducted on β-Li TiO and Li SiO to compare several of their radiation damage-related properties at 0 K. Overall, Li TiO was found to be more tolerant to irradiation damage than Li SiO , which is in qualitative agreement with recent experiments. For instance, Li TiO was found to amorphize at 0.55 dpa, while Li SiO amorphized at 0.25 dpa itself. Including the polarization of the O atom while modeling cascades in Li TiO was found to predict a more realistic cascade behavior and defect production. The threshold displacement energies and diffusion coefficients of atoms were calculated for both the materials. Li diffusion was found to be highest when compared to other atoms. For Li SiO , the existing interatomic potential predicted an Li diffusion coefficient which is nearly two orders of magnitude higher than what is seen for Li TiO . Moreover, this potential predicted Li diffusion at temperatures as low as 583K, making it impossible to compare finite temperature primary damage with Li TiO . read less USED (low confidence) M. Dmitrenko et al., “MODIFICATION STRATEGIES OF POLYACRYLONITRILE ULTRAFILTRATION MEMBRANE USING TIO2 FOR ENHANCED ANTIFOULING PERFORMANCE IN WATER TREATMENT,” Separation and Purification Technology. 2022. link Times cited: 24 USED (low confidence) G. Mancardi, M. Alberghini, N. Aguilera-Porta, M. Calatayud, P. Asinari, and E. Chiavazzo, “Multi-Scale Modelling of Aggregation of TiO2 Nanoparticle Suspensions in Water,” Nanomaterials. 2022. link Times cited: 3 Abstract: Titanium dioxide nanoparticles have risen concerns about the… read moreAbstract: Titanium dioxide nanoparticles have risen concerns about their possible toxicity and the European Food Safety Authority recently banned the use of TiO2 nano-additive in food products. Following the intent of relating nanomaterials atomic structure with their toxicity without having to conduct large-scale experiments on living organisms, we investigate the aggregation of titanium dioxide nanoparticles using a multi-scale technique: starting from ab initio Density Functional Theory to get an accurate determination of the energetics and electronic structure, we switch to classical Molecular Dynamics simulations to calculate the Potential of Mean Force for the connection of two identical nanoparticles in water; the fitting of the latter by a set of mathematical equations is the key for the upscale. Lastly, we perform Brownian Dynamics simulations where each nanoparticle is a spherical bead. This coarsening strategy allows studying the aggregation of a few thousand nanoparticles. Applying this novel procedure, we find three new molecular descriptors, namely, the aggregation free energy and two numerical parameters used to correct the observed deviation from the aggregation kinetics described by the Smoluchowski theory. Ultimately, molecular descriptors can be fed into QSAR models to predict the toxicity of a material knowing its physicochemical properties, enabling safe design strategies. read less USED (low confidence) D. Sahoo, P. Chaudhuri, and N. Swaminathan, “A molecular dynamics study of displacement cascades and radiation induced amorphization in Li2TiO3,” Computational Materials Science. 2021. link Times cited: 11 USED (low confidence) H. Yang, B. Sun, Y. Zhu, D. Yin, and J. Yao, “Critical role of surficial activity in the sintering process of TiO2 nanoparticles by molecular dynamics simulation,” Powder Technology. 2021. link Times cited: 4 USED (low confidence) F. Grigoriev, V. Sulimov, and A. Tikhonravov, “Structure and properties of the low-energy deposited TiO2 thin films: results of the molecular dynamics simulation,” Journal of Physics: Conference Series. 2021. link Times cited: 0 Abstract: The classical molecular dynamics simulation of the low-energ… read moreAbstract: The classical molecular dynamics simulation of the low-energy glancing angle deposition of titanium dioxide films is performed. The deposition angle varies from 60° to 80°. It is found that the film structure consists of parallel slanted columns which lead to the anisotropy of films properties. The difference between the main components of the refractive index tensor is about 0.14, which is close to the values obtained for high-energy titanium dioxide films and larger than 0.03 obtained earlier for silicon dioxide films. read less USED (low confidence) Y. Liu, W.-X. Wang, Z. Jiang, and Z. Zhang, “Molecular dynamics study on the shear strain induced martensite-like transformation between rutile and α-PbO2 phase of titanium dioxide,” Journal of Alloys and Compounds. 2021. link Times cited: 1 USED (low confidence) I. Zeydabadi-Nejad, N. Zolfaghari, M. M. Mashhadi, M. Baghani, and M. Baniassadi, “Anatase TiO2 nanotubes as Li-ion battery anodes: A molecular dynamics study of Li-ion adsorption on anatase nanotubes,” Sustainable Energy Technologies and Assessments. 2021. link Times cited: 4 USED (low confidence) D. Li, Z. Liang, W. Zhang, and C. Zhang, “One‐step synthesis of Cu/N co‐doped TiO
2
nanocomposites with enhanced photocatalytic activities under visible‐light irradiation,” Micro & Nano Letters. 2021. link Times cited: 5 USED (low confidence) D. S. Stepaniuk et al., “Solvatochromism of a D205 indoline dye at the interface of a small TiO2-anatase nanoparticle in acetonitrile: a combined molecular dynamics simulation and DFT calculation study,” Molecular Simulation. 2021. link Times cited: 1 Abstract: ABSTRACT A combined molecular dynamics (MD) simulation and d… read moreAbstract: ABSTRACT A combined molecular dynamics (MD) simulation and density functional theory (DFT) calculations were used to investigate the effect of the acetonitrile (ACN) solution on the absorption and the charge transfer in a D205 indoline dye at the interface of a TiO2 nanoparticle. DFT calculations were carried out to estimate the equilibrium geometry of a small Ti30O62H4-anatase nanoparticle and to derive interaction parameters for bidentate binding of a D205 dye to TiO2. A series of the D205 dye configurations anchored to Ti30O62H4 were generated from the MD simulations and used as input for the time-dependent DFT (TD-DFT) calculations. We found that the immersion of the D205-Ti30O62H4 composite system into the polar ACN environment results in conformational changes of the dye moiety, which are accompanied by the solvatochromic redshift of its long-wavelength absorption band up to 1900 cm-1. Our results show that the HOMO and LUMO energy level alignment of the dye and the nanoparticle suggests a favourable driving force for charge transfer from the dye to TiO2. The MD/TD-DFT-estimated solvatochromic shift for the D205 dye at the TiO2/ACN interface is in good agreement with the experiment, showing that such computational approach enables reliable predictions of optical properties of other dye-TiO2 composites in solution. read less USED (low confidence) N. Wood et al., “An atomistic modelling investigation of the defect chemistry of SrTiO3 and its Ruddlesden-Popper phases, Srn+1TinO3n+1 (n = 1–3),” Journal of Solid State Chemistry. 2021. link Times cited: 6 USED (low confidence) S. Motta, P. Siani, A. Levy, and C. D. Valentin, “Exploring the drug loading mechanism of photoactive inorganic nanocarriers through molecular dynamics simulations,” Nanoscale. 2021. link Times cited: 2 Abstract: Inorganic nanoparticles are gaining increasing attention as … read moreAbstract: Inorganic nanoparticles are gaining increasing attention as drug carriers because they respond to external physical stimuli, allowing therapy to be combined with diagnosis. Their drawback is low drug loading capacity, which can be improved by proper and efficacious functionalization. In this computational study, we take TiO2 spherical nanoparticles as prototype photoresponsive inorganic nanoparticles and we fully decorate them with two different types of bifunctional ligands: TETTs and DOPACs, which present different surface anchoring groups (silanol or catechol) but the same drug tethering COOH group, although in different concentrations (3 vs. 1), thus causing different steric hindrances. Then, we put these two types of nanocarriers in bulk water and in the presence of several DOX molecules and let the systems evolve through molecular dynamics (MD) simulations, clearly observing drug loading on the nanocarriers. This comparative MD study allows the investigation of the loading mechanism, performance of a conformational analysis and establishment of the guiding interactions through an energy decomposition analysis. We learn that DOX mostly interacts with the functionalized NPs through electrostatics, as a consequence of the protonated amino group, although several H-bonds are also established both with the ligands and with the oxide surface. Different ligands induce a different electrostatic potential around the NP; therefore, those which lead to the formation of more negative hotspots (here TETTs) are found to favour DOX binding. The leading role of electrostatics can provide a rational explanation for a pH-dependent drug release mechanism that is often invoked for DOX when reaching diseased cells because under anomalous acidic conditions both the NP surface and the carboxylate groups of the ligands are expected to get protonated, which of course would weaken, if not totally quench, the interaction of the nanocarrier with protonated DOX. read less USED (low confidence) A. Kupferer, A. Holm, A. Lotnyk, S. Mändl, and S. G. Mayr, “Compositional Patterning in Carbon Implanted Titania Nanotubes,” Advanced Functional Materials. 2021. link Times cited: 6 Abstract: Ranging from novel solar cells to smart biosensors, titania … read moreAbstract: Ranging from novel solar cells to smart biosensors, titania nanotube arrays constitute a highly functional material for various applications. A promising route to modify material characteristics while preserving the amorphous nanotube structure is present when applying low‐energy ion implantation. In this study, the interplay of phenomenological effects observed upon implantation of low fluences in the unique 3D structure is reported: sputtering versus readsorption and plastic flow, amorphization versus crystallization and compositional patterning. Patterning within the oxygen and carbon subsystem is revealed using transmission electron microscopy. By applying a Cahn–Hilliard approach within the framework of driven alloys, characteristic length scales are derived and it is demonstrated that compositional patterning is expected on free enthalpy grounds, as predicted by density functional theory based ab initio calculations. Hence, an attractive material with increased conductivity for advanced devices is provided. read less USED (low confidence) H. Qi et al., “Size‐Confined Effects of Nanostructures on Fibronectin‐Induced Macrophage Inflammation on Titanium Implants,” Advanced Healthcare Materials. 2021. link Times cited: 11 Abstract: Macrophage activation determines the fate of biomaterials im… read moreAbstract: Macrophage activation determines the fate of biomaterials implantation. Though researches have shown that fibronectin (FN) is highly involved in integrin‐induced macrophage activation on biomaterials, the mechanism of how nanosized structure affects macrophage behavior is still unknown. Here, titanium dioxide nanotube structures with different sizes are fabricated to investigate the effects of nanostructure on macrophage activation. Compared with larger sized nanotubes and smooth surface, 30 nm nanotubes exhibit considerable lesser pro‐inflammatory properties on macrophage differentiation. Confocal protein observation and molecular dynamics simulation show that FN displays conformation changes on different nanotubes in a feature of “size‐confined,” which causes the hiding of Arg‐Gly‐Asp (RGD) domain on other surfaces. The matching size of nanotube with FN allows the maximum exposure of RGD on 30 nm nanotubes, activating integrin‐mediated focal adhesion kinase (FAK)‐phosphatidylinositol‐3 kinase γ (PI3Kγ) pathway to inhibit nuclear factor kappa B (NF‐κB) signaling. In conclusion, this study explains the mechanism of nanostructural‐biological signaling transduction in protein and molecular levels, as well as proposes a promising strategy for surface modification to regulate immune responses on bioimplants. read less USED (low confidence) N. Goga et al., “A Review of Recent Developments in Molecular Dynamics Simulations of the Photoelectrochemical Water Splitting Process,” Catalysts. 2021. link Times cited: 8 Abstract: In this review, we provide a short overview of the Molecular… read moreAbstract: In this review, we provide a short overview of the Molecular Dynamics (MD) method and how it can be used to model the water splitting process in photoelectrochemical hydrogen production. We cover classical non-reactive and reactive MD techniques as well as multiscale extensions combining classical MD with quantum chemical and continuum methods. Selected examples of MD investigations of various aqueous semiconductor interfaces with a special focus on TiO2 are discussed. Finally, we identify gaps in the current state-of-the-art where further developments will be needed for better utilization of MD techniques in the field of water splitting. read less USED (low confidence) M. Sanjeev, M. Gilbert, and S. Murphy, “Anisotropic thermal conductivity in Li2TiO3 ceramic breeder materials,” Fusion Engineering and Design. 2021. link Times cited: 2 USED (low confidence) A. Holm and S. G. Mayr, “Glassy and ballistic dynamics in collision cascades in amorphous
TiO2
: Combined molecular dynamics and Monte Carlo based studies across energy scales,” Physical Review B. 2021. link Times cited: 1 USED (low confidence) N. Jakse, C. M. S. Alvares, and A. Pisch, “Ab initio based interionic interactions in calcium aluminotitanate oxide melts: structure and diffusion,” Journal of Physics: Condensed Matter. 2021. link Times cited: 1 Abstract: Calcium aluminotitanate (CaO–Al2O3–TiO2) ternary oxides are … read moreAbstract: Calcium aluminotitanate (CaO–Al2O3–TiO2) ternary oxides are of fundamental interest in Materials as well as Earth and environmental science, and a key system for several industrial applications. As their properties at the atomic scale are scarcely known, interionic interactions for the melts are built from a bottom up strategy consisting in fitting first only Al2O3, CaO and TiO2 single oxide compounds separately with a unified description of the oxygen charge and O–O interaction term. For this purpose, a mean-square difference minimization of the partial pair-correlation functions with respect to the ab initio reference was performed. The potentials for the ternary oxide are finally built straightforwardly by adding purely Coulomb terms for dissimilar cation–cation interactions without further fit. This general and unified approach is transferable and successfully describes the structural and diffusion properties of the three single oxides as well as the ternary melts simultaneously. A possible underlying structural mechanism at the origin of the diffusion evolution with TiO2 content is proposed based on the formation of Ti induced triply bonded oxygen. read less USED (low confidence) V. Sirotkin, “Molecular dynamic simulation of rutile surface bombardment by argon cluster ions,” Vacuum. 2021. link Times cited: 2 USED (low confidence) S. C. Endres, L. Ciacchi, and L. Mädler, “A review of contact force models between nanoparticles in agglomerates, aggregates, and films,” Journal of Aerosol Science. 2021. link Times cited: 51 USED (low confidence) H. Jami and A. Jabbarzadeh, “Molecular simulation of high-velocity deposition of titanium dioxide nanoparticles on titanium,” Applied Surface Science. 2021. link Times cited: 20 USED (low confidence) M. M. Blazhynska, D. S. Stepaniuk, V. Koverga, A. Kyrychenko, A. Idrissi, and O. Kalugin, “Structure and dynamics of TiO2-anchored D205 dye in ionic liquids and acetonitrile,” Journal of Molecular Liquids. 2021. link Times cited: 2 USED (low confidence) A. Radhi and K. Behdinan, “Characterization of Ultra‐High Temperature and Polymorphic Ceramics.” 2021. link Times cited: 0 USED (low confidence) X. Wu, P. Hao, F. He, Z. Yao, and X. Zhang, “Molecular dynamics simulations of BSA absorptions on pure and formate-contaminated rutile (1 1 0) surface,” Applied Surface Science. 2020. link Times cited: 5 USED (low confidence) Y. Ren, Y. Zhang, Q. Mao, and H. Pitsch, “Amorphous-to-Crystalline Transition during Sintering of Nascent TiO2 Nanoparticles in Gas-Phase Synthesis: A Molecular Dynamics Study,” Journal of Physical Chemistry C. 2020. link Times cited: 16 USED (low confidence) F. Grigoriev, V. Sulimov, and A. Tikhonravov, “Application of a large-scale molecular dynamics approach to modelling the deposition of TiO2 thin films,” Computational Materials Science. 2020. link Times cited: 3 USED (low confidence) E. Ulyanova et al., “Local environment of CdS nanoparticles incorporated into anatase/brookite matrix via sol-gel route: HRTEM, Raman spectroscopy and MD simulation,” Materials today communications. 2020. link Times cited: 2 USED (low confidence) H. Hong, S. A. Song, and S. Kim, “Phase transformation of poly (vinylidene fluoride)/TiO2 nanocomposite film prepared by microwave-assisted solvent evaporation: An experimental and molecular dynamics study,” Composites Science and Technology. 2020. link Times cited: 17 USED (low confidence) Z.-jian Liu, Q. Cheng, Y. Wang, K. Li, R.-rong Wang, and J. Zhang, “The interaction of nanoparticulate Fe3O4 during the diffusion-limited aggregation process: A molecular dynamics simulation,” Powder Technology. 2020. link Times cited: 9 USED (low confidence) P. Siani, S. Motta, L. Ferraro, A. Dohn, and C. D. Valentin, “Dopamine-Decorated TiO2 Nanoparticles in Water: A QM/MM vs an MM Description,” Journal of Chemical Theory and Computation. 2020. link Times cited: 4 Abstract: Nanoparticle functionalization is a modern strategy in nanot… read moreAbstract: Nanoparticle functionalization is a modern strategy in nanotechnology to build up devices for several applications. Modeling fully decorated metal oxide nanoparticles of realistic size (few nanometers) in an aqueous environment is a challenging task. In this work, we present a case study relevant for solar-light exploitation and for biomedical applications, i.e., a dopamine-functionalized TiO2 nanoparticle (1700 atoms) in bulk water, for which we have performed an extensive comparative investigation with both MM and QM/MM approaches of the structural properties and of the conformational dynamics. We have used a combined multiscale protocol for a more efficient exploration of the complex conformational space. On the basis of the results of this study and of some QM and experimental data, we have defined strengths and limitations of the existing force field parameters. Our findings will be useful for an improved modeling and simulation of many other similar hybrid bioinorganic nanosystems in an aqueous environment that are pivotal in a broad range of nanotechnological applications. read less USED (low confidence) S. Ikram et al., “A novel approach to simultaneously enhance the Seebeck coefficient and electrical conductivity in rutile phase of TiO2 nanostructures,” Arabian Journal of Chemistry. 2020. link Times cited: 13 USED (low confidence) J. Ryu, T. Oda, and H. Tanigawa, “Comparison and validation of the lattice thermal conductivity formulas used in equilibrium molecular dynamics simulations for binary systems,” Computational Materials Science. 2020. link Times cited: 1 USED (low confidence) A. G. Newton and K. Kwon, “Classical mechanical simulations of layer- and tunnel-structured manganese oxide minerals,” Geochimica et Cosmochimica Acta. 2020. link Times cited: 12 USED (low confidence) A. Timoumi, H. Albetran, H. Alamri, S. Alamri, and I. Low, “Impact of annealing temperature on structural, morphological and optical properties of GO-TiO2 thin films prepared by spin coating technique,” Superlattices and Microstructures. 2020. link Times cited: 37 USED (low confidence) M. Rafique et al., “Investigation of Photocatalytic and Seed Germination Effects of TiO2 Nanoparticles Synthesized by Melia azedarach L. Leaf Extract,” Journal of Inorganic and Organometallic Polymers and Materials. 2019. link Times cited: 26 USED (low confidence) A. Reinhardt, C. Pickard, and B. Cheng, “Predicting the phase diagram of titanium dioxide with random search and pattern recognition.,” Physical chemistry chemical physics : PCCP. 2019. link Times cited: 17 Abstract: Predicting phase stabilities of crystal polymorphs is centra… read moreAbstract: Predicting phase stabilities of crystal polymorphs is central to computational materials science and chemistry. Such predictions are challenging because they first require searching for potential energy minima and then performing arduous free-energy calculations to account for entropic effects at finite temperatures. Here, we develop a framework that facilitates such predictions by exploiting all the information obtained from random searches of crystal structures. This framework combines automated clustering, classification and visualisation of crystal structures with machine-learning estimation of their enthalpy and entropy. We demonstrate the framework on the technologically important system of TiO2, which has many polymorphs, without relying on prior knowledge of known phases. We find a number of new phases and predict the phase diagram and metastabilities of crystal polymorphs at 1600 K, benchmarking the results against full free-energy calculations. read less USED (low confidence) D. Selli, M. Tawfilas, M. Mauri, R. Simonutti, and C. D. Valentin, “Optimizing PEGylation of TiO2 Nanocrystals through a Combined Experimental and Computational Study,” Chemistry of Materials. 2019. link Times cited: 18 Abstract: PEGylation of metal oxide nanoparticles is the common approa… read moreAbstract: PEGylation of metal oxide nanoparticles is the common approach to improve their biocompatibility and in vivo circulation time. In this work, we present a combined experimental and theoretical study to determine the operating condition that guarantee very high grafting densities, which are desirable in any biomedical application. Moreover, we present an insightful conformational analysis spanning different coverage regimes and increasing polymer chain lengths. Based on 13C NMR measurements and molecular dynamics simulations, we show that classical and popular models of polymer conformation on surfaces fail in determining the mushroom-to-brush transition point and prove that it actually takes place only at rather high grafting density values. read less USED (low confidence) H. Badorreck et al., “Correlation of structural and optical properties using virtual materials analysis.,” Optics express. 2019. link Times cited: 15 Abstract: Thin film growth of ${\textrm{TiO}}_2$TiO2 by physical vapor… read moreAbstract: Thin film growth of ${\textrm{TiO}}_2$TiO2 by physical vapor deposition processes is simulated in the Virtual Coater framework resulting in virtual thin films. The simulations are carried out for artificial, simplified deposition conditions as well as for conditions representing a real coating process. The study focuses on porous films which exhibit a significant anisotropy regarding the atomistic structure and consequently, to the index of refraction. A method how to determine the effective anisotropic index of refraction of virtual thin films by the effective medium theory is developed. The simulation applies both, classical molecular dynamics as well as kinetic Monte Carlo calculations, and finally the properties of the virtual films are compared to experimentally grown films especially analyzing the birefringence in the evaluation. read less USED (low confidence) E. Inclan and M. Yoon, “Performance of biologically inspired algorithms tuned on TiO2 nanoparticle benchmark system,” Computational Materials Science. 2019. link Times cited: 1 USED (low confidence) H. Nada, M. Kobayashi, and M. Kakihana, “Anisotropy in Stable Conformations of Hydroxylate Ions between the 001 and 110 Planes of TiO2 Rutile Crystals for Glycolate, Lactate, and 2-Hydroxybutyrate Ions Studied by Metadynamics Method,” ACS Omega. 2019. link Times cited: 4 Abstract: Control over TiO2 rutile crystal growth and morphology using… read moreAbstract: Control over TiO2 rutile crystal growth and morphology using additives is essential for the development of functional materials. Computer simulation studies on the thermodynamically stable conformations of additives at the surfaces of rutile crystals contribute to understanding the mechanisms underlying this control. In this study, a metadynamics method was combined with molecular dynamics simulations to investigate the thermodynamically stable conformations of glycolate, lactate, and 2-hydroxybutyrate ions at the {001} and {110} planes of rutile crystals. Two simple atom–atom distances were selected as collective variables for the metadynamics method. At the {001} plane, a conformation in which the COO– group was oriented toward the surface was found to be the most stable for the lactate and 2-hydroxybutyrate ions, whereas a conformation in which the COO– group was oriented toward water was the most stable for the glycolate ion. At the {110} plane, a conformation in which the COO– group was oriented toward the surface was the most stable for all three hydroxylate ions, and a second most stable conformation was also observed for the lactate ion at positions close to the {110} plane. For all three hydroxylate ions (α-hydroxycarboxylate ions), the stability of the most stable conformation was higher for the {110} plane than for the {001} plane. At both planes, the stability of the most stable conformation was highest for the 2-hydroxybutyrate ion and lowest for the glycolate ion. Supposing that all three hydroxylate ions serve to decrease the surface free energy at the rutile surface and that a more stable conformation at the rutile surface leads to a greater decrease in the surface free energy, the present results partially explain experimentally observed differences in the changes in growth rate and morphology of rutile crystals in the presence of glycolic, lactic, and 2-hydroxybutyric acids. read less USED (low confidence) A. M. Escatllar, Á. Morales‐García, F. Illas, and S. Bromley, “Efficient preparation of TiO2 nanoparticle models using interatomic potentials.,” The Journal of chemical physics. 2019. link Times cited: 7 Abstract: Computational modeling has proven to be extremely useful for… read moreAbstract: Computational modeling has proven to be extremely useful for understanding how the morphology, size, and structure of TiO2 nanoparticles (NPs) affect their electronic properties and their usage in targeted applications (e.g., photocatalysis). Density functional theory (DFT) based calculations of NPs (on the order of hundreds to thousands of atoms) are, however, computationally highly demanding. Herein, we show that interatomic potentials (IPs) can provide a highly computationally efficient means to prepare NP structures which are sufficiently accurate to significantly reduce the computational cost of subsequent DFT calculations. We first compare the direct DFT optimization of faceted NPs directly cut from the anatase bulk crystal with the same calculation where the NP is preoptimized using four different IPs. We then establish the subsequent computational time saving for the respective complete DFT optimizations. We show that IP-based preoptimizing can greatly speed up DFT convergence, with speed-ups of 3×-10× for single point DFT energy evaluations. Moreover, as IP preoptimized NP structures can be closer to those of DFT energy minima, further speed-ups of 2× for DFT structure optimizations can be achieved. Finally, taking NPs derived from anatase spherical cuts, we show that IP-based molecular dynamics annealing gives rise to significant structural reconstruction with an associated high energetic stabilization, as confirmed by DFT calculations. Although similar results can be achieved using DFT tight binding methods, IP-based methods are 3-4 orders of magnitude faster and thus provide a particularly highly computationally efficient route to the preparation and design of large and diverse NP sets. read less USED (low confidence) D. Biriukov, O. Kroutil, M. Kabelác, M. Ridley, M. Machesky, and M. Předota, “Oxalic Acid Adsorption on Rutile: Molecular Dynamics and ab Initio Calculations.,” Langmuir : the ACS journal of surfaces and colloids. 2019. link Times cited: 12 Abstract: Detailed analysis of the adsorption of oxalic acid ions, tha… read moreAbstract: Detailed analysis of the adsorption of oxalic acid ions, that is, oxalate and hydrogenoxalate, on the rutile (110) surface was carried out using molecular dynamics augmented by free energy calculations and supported by ab initio calculations. The predicted adsorption on perfect nonhydroxylated and hydroxylated surfaces with surface charge density from neutral to +0.208 C/m2 corresponding to pH values of about 6 and 3.7, respectively, agrees with experimental adsorption data and charge-distribution multisite ion complexation model predictions obtained using the most favorable surface complexes identified in our simulations. We found that outer-sphere complexes are the most favorable, owing to strong hydrogen binding of oxalic acid ions with surface hydroxyls and physisorbed water. The monodentate complex, the most stable among inner-sphere complexes, was about 15 kJ/mol higher in energy, but separated by a large energy barrier. Other inner-sphere complexes, including some previously suggested in the literature as likely adsorption structures such as bidentate and chelate complexes, were found to be unstable both by classical and by ab initio modeling. Both the surfaces and (hydrogen)oxalate ions were modeled using charges scaled to 75% of the nominal values in accord with the electronic continuum theory and our earlier parameterization of (hydrogen)oxalate ions, which showed that nominal charges exaggerate ion-water interactions. read less USED (low confidence) C. Mao, J. Sampath, K. Sprenger, G. Drobny, and J. Pfaendtner, “Molecular Driving Forces in Peptide Adsorption to Metal Oxide Surfaces.,” Langmuir : the ACS journal of surfaces and colloids. 2019. link Times cited: 30 Abstract: Molecular recognition between peptides and metal oxide surfa… read moreAbstract: Molecular recognition between peptides and metal oxide surfaces is a fundamental process in biomineralization, self-assembly, and biocompatibility. Yet, the underlying driving forces and dominant mechanisms remain unclear, bringing obstacles to understand and control this process. To elucidate the mechanism of peptide/surface recognition, specifically the role of serine phosphorylation, we employed molecular dynamics simulation and metadynamics-enhanced sampling to study five artificial peptides, DDD, DSS, DpSpS, DpSpSGKK, and DpSKGpSK, interacting with two surfaces: rutile TiO2 and quartz SiO2. On both surfaces, we observe that phosphorylation increases the binding energy. However, the interfacial peptide conformation reveals a distinct binding mechanism on each surface. We also study the impact of peptide sequence to binding free energy and interfacial conformation on both surfaces, specifically the impact on the behavior of phosphorylated serine. Finally, the results are discussed in context of prior studies investigating the role of serine phosphorylation in peptide binding to silica. read less USED (low confidence) P. Grammatikopoulos, M. Sowwan, and J. Kioseoglou, “Computational Modeling of Nanoparticle Coalescence,” Advanced Theory and Simulations. 2019. link Times cited: 68 Abstract: The coalescence of nanoclusters fabricated in the gas phase … read moreAbstract: The coalescence of nanoclusters fabricated in the gas phase is a fundamental growth mechanism determining cluster shapes, sizes, compositions, and structures, with resultant effects on practically all of their physical and chemical properties. Furthermore, coalescence can affect properties of larger structures that consist of nanoparticles as their elementary building blocks, such as the fractal dimension of cluster aggregates and the porosity and conductance of thin films. Therefore, it comes as no surprise that a great body of research, both experimental and theoretical, has focused on nanoparticle coalescence over the course of the past few decades. This review attempts to summarize the most important recent results from computational studies on nanoparticle coalescence and draw parallels between theoretical and experimental findings. The approach used here aspires to explain nanoparticle coalescence within the framework of a single intuitive narrative by integrating previous results obtained using various methods by the authors and others. Simultaneously, it is discussed where understanding and controlling (i.e., enhancing or inhibiting) nanoparticle coalescence can have great technological interest. read less USED (low confidence) M. D. Pushpa et al., “Influence of pyrolytic temperature on optoelectronic properties and the energy harvesting applications of high pressure TiO2 thin films,” Vacuum. 2019. link Times cited: 9 USED (low confidence) I. Zeydabadi-Nejad, N. Zolfaghari, M. Mosavi-Mashhadi, and M. Baniassadi, “Exceptional behavior of anatase TiO2 nanotubes in axial loading: A molecular dynamics study of the effect of surface wrinkles,” Computational Materials Science. 2019. link Times cited: 6 USED (low confidence) J. Liu et al., “Pressure Dependence of Electrical Conductivity of Black Titania Hydrogenated at Different Temperatures,” The Journal of Physical Chemistry C. 2019. link Times cited: 9 Abstract: Temperature can control the degree of hydrogenation of titan… read moreAbstract: Temperature can control the degree of hydrogenation of titania (i.e., black TiO2), determining the defect chemistry and hence its optical absorption and electrical conductivity that are key to the photocatalytic activity. However, how pressure affects the two key factors is unknown. In this work, we used a diamond anvil cell to produce the required high pressure (HP) and studied the pressure dependences of the structure change, the electrical conductivity, and the light absorption of black titania using HP X-ray diffraction, Raman/UV–vis spectroscopy, and electrical transport measurements. Results reveal that accompanying the HP phase transition the electrical conductivity exhibits complex variation with pressure, in good accord with the band gap changes of involved HP phases as a function of pressure. This confirms the assumption that pressure affects the electrical conductivity of black titania via controlling the number of free electrons (holes) distributed in the conduction (valence) band, which is in... read less USED (low confidence) M.-hao Wang, Q. Wang, K. Wang, and X. Lu, “Functionalized TiO2 Surfaces Facilitate Selective Receptor-Recognition and Modulate Biological Function of Bone Morphogenetic Protein-2,” The Journal of Physical Chemistry C. 2018. link Times cited: 7 Abstract: Titanium dioxide (TiO2) is a promising biomedical material b… read moreAbstract: Titanium dioxide (TiO2) is a promising biomedical material because it can be modified with various functional groups. However, the mechanism of the interaction between functionalized TiO2 and biomolecules, especially how the modified TiO2 regulates subsequent protein functions, still needs further investigation. In this study, we studied the interaction of bone morphogenetic protein-2 (BMP-2) with hydroxyl- and phosphite-grafted TiO2 surfaces. A set of force field parameters was developed for hydroxyl and phosphite groups on TiO2 surfaces, and the adsorption energy between the surface of the functionalized TiO2 and BMP-2 was calculated. Different coverages of functional groups were applied to the surface to investigate the influence of the functional group density. Grafting phosphite groups on the surface of TiO2 can significantly increase the adsorption energy of the protein and change the orientation of BMP-2 so that the wrist epitope of the BMP-2 molecules is pointing upward. This configuration specifi... read less USED (low confidence) L. Momenzadeh, B. Moghtaderi, I. Belova, and G. Murch, “Determination of the lattice thermal conductivity of the TiO2 polymorphs rutile and anatase by molecular dynamics simulation,” Computational Condensed Matter. 2018. link Times cited: 9 USED (low confidence) M. Suhail, B. Puliyeri, P. Chaudhuri, R. Annabattula, and N. Swaminathan, “Molecular Dynamics Simulation of Primary Damage in β-Li2TiO3,” Fusion Engineering and Design. 2018. link Times cited: 7 USED (low confidence) D. Biriukov, O. Kroutil, and M. Předota, “Modeling of solid-liquid interfaces using scaled charges: rutile (110) surfaces.,” Physical chemistry chemical physics : PCCP. 2018. link Times cited: 23 Abstract: Electronic continuum correction (ECC) has been proven to bri… read moreAbstract: Electronic continuum correction (ECC) has been proven to bring significant improvement in the modeling of interactions of ions (especially multivalent) in aqueous solutions. We present a generalization and the first application of this approach to modeling solid-liquid interfaces, which are omnipresent in physical chemistry, geochemistry, and biophysics. Scaling charges of the top layer of surface atoms makes the existing solid models compatible with the ECC models of ions and molecules, allowing the use of modified force fields for a more accurate investigation of interactions of various metal and metal-oxide surfaces with aqueous solutions, including complex biomolecules and multivalent ions. We have reparametrized rutile (110) models with different surface charge densities (from 0 to -0.416 C m-2) and adopted/developed scaled charge force fields for ions, namely Na+, Rb+, Sr2+, and Cl-. A good agreement of the obtained molecular dynamics (MD) data with X-ray experiments and previously reported MD results was observed, but changes in the occupancy of various adsorption sites were observed and discussed in detail. read less USED (low confidence) H. Liu, J. Lu, T. Zheng, D. Liu, and F. Cui, “Molecular Dynamics Simulation of Natural Organic Matter–TiO2 Nanoparticle Interaction in Aqueous Environment: Effects of Ca2+ and Na+ Ions,” Environmental Engineering Science. 2018. link Times cited: 0 USED (low confidence) G. Mancardi, C. H. Tamargo, U. Terranova, and N. D. de Leeuw, “Calcium Phosphate Deposition on Planar and Stepped (101) Surfaces of Anatase TiO2: Introducing an Interatomic Potential for the TiO2/Ca-PO4/Water Interface.,” Langmuir : the ACS journal of surfaces and colloids. 2018. link Times cited: 5 Abstract: Titanium is commonly employed in orthopaedic and dental surg… read moreAbstract: Titanium is commonly employed in orthopaedic and dental surgery, owing to its good mechanical properties. The titanium metal is usually passivated by a thin layer of its oxide, and in order to promote its integration with the biological tissue, it is covered by a bioactive material such as calcium phosphate (CaP). Here, we have investigated the deposition of calcium and phosphate species on the anatase phase of titanium dioxide (TiO2) using interatomic potential-based molecular dynamics simulations. We have combined different force fields developed for CaP, TiO2, and water, benchmarking the results against density functional theory calculations. On the basis of our study, we consider that the new parameters can be used successfully to study the nucleation of CaP on realistic anatase and rutile TiO2 nanoparticles, including surface defects. read less USED (low confidence) X. Zhang, H. Gao, and X. Li, “Atomistic simulations of superplasticity and amorphization of nanocrystalline anatase TiO2,” Extreme Mechanics Letters. 2018. link Times cited: 7 USED (low confidence) A. Radhi, V. Iacobellis, and K. Behdinan, “A Cumulative Approach to Crystalline Structure Characterization in Atomistic Simulations,” The Journal of Physical Chemistry C. 2018. link Times cited: 5 Abstract: Crystalline characterization poses a challenge when atomic d… read moreAbstract: Crystalline characterization poses a challenge when atomic deformation and phase transformation are occurring in an atomic simulation. Crystalline solids are typically characterized by parameters used to classify local atomic arrangements in order to extract features such as crack tips, dislocations, and free surfaces. One such characterization parameter, the common neighborhood parameter (CNP), has been used as an approach to characterize those features with an enhanced formulation applicable to non-monoatomic interactions. The present work introduces a novel approach that extends the CNP to characterize crystalline structures by means of cumulative common neighborhood parametrization (CCNP) for arbitrary structures. The method is compared with the centrosymmetry parameter (CSP) and the common neighborhood parameter (CNA). The methods were applied to a molecular dynamics (MD) simulation of uniaxial tension in an aluminum nanowire. The results showed CCNP’s superior performance in detecting distinct surfa... read less USED (low confidence) Q. Xiong, Z. Sha, Q. Pei, T. Kitamura, and Z.-huan Li, “Thermal damage and ablation behavior of graphene induced by ultrafast laser irradiation,” Journal of Thermal Stresses. 2018. link Times cited: 7 Abstract: Ultrafast laser-induced damage and ablation of graphene is t… read moreAbstract: Ultrafast laser-induced damage and ablation of graphene is the one of the most critical parts of precise nanopatterning of graphene by using laser ablation. In this article, we have studied the local damage and ablation behavior of monolayer graphene irradiated by femtosecond single pulse laser using molecular dynamics simulation. A theoretical model of phonon-dominated absorption of laser energy is proposed to describe the interaction between graphene and femtosecond single pulse laser. The simulation results based on this model are quantitatively consistent with experimental and theoretical ones. Furthermore, the effects of laser fluences on the atomic ablation behavior and nanogroove generation are investigated. The results show that the relationship between depth of the induced ablation and laser fluence follows a logarithmic function instead of a simple linear relationship. These results will be useful in providing guidance in femtosecond laser processing of graphene. read less USED (low confidence) Q. Yang and G. Y. Grest, “Molecular-level insight of gas transport in composite poly (4-methyl-2-pentyne) and nanoparticles of titanium dioxide,” European Polymer Journal. 2018. link Times cited: 5 USED (low confidence) L. Peña-Parás et al., “Effects of substrate surface roughness and nano/micro particle additive size on friction and wear in lubricated sliding,” Tribology International. 2018. link Times cited: 41 USED (low confidence) A. Chitnis, B. Chakraborty, B. Tripathi, A. K. Tyagi, and N. Garg, “High pressure stability of lithium metatitanate and metazirconate: Insight from experiments & ab-initio calculations,” Journal of Nuclear Materials. 2018. link Times cited: 6 USED (low confidence) A. Cuko, M. Calatayud, and S. Bromley, “Stability of mixed-oxide titanosilicates: dependency on size and composition from nanocluster to bulk.,” Nanoscale. 2018. link Times cited: 15 Abstract: Nanostructured titanosilicate materials based upon interfaci… read moreAbstract: Nanostructured titanosilicate materials based upon interfacing nano-TiO2 with nano-SiO2 have drawn much attention due to their huge potential for applications in a diverse range of important fields including gas sensing, (photo)catalysis, solar cells, photonics/optical components, tailored multi-(bio)functional supports and self-cleaning coatings. In each case it is the specific mixed combination of the two SiO2 and TiO2 nanophases that determines the unique properties of the final nanomaterial. In the bulk, stoichiometric mixing of TiO2 with SiO2 is limited by formation of segregated TiO2 nanoparticles or metastable glassy phases and more controlled disperse crystalline mixings only occur at small fractions of TiO2 (<15 wt%). In order to more fully understand the stability of nano-SiO2 and nano-TiO2 combinations with respect to composition and size, we employ accurate all-electron density functional calculations to evaluate the mixing energy in (TixSi1-xO2)n nanoclusters with a range of sizes (n = 2-24) having different titania molar fractions (x = 0-1). We derive all nanoclusters from a dedicated global optimisation procedure to help ensure that they are the most energetically stable structures for their size and composition. We also consider a selection of representative intimately mixed crystalline solid phase (TixSi1-xO2)bulk systems for comparison. In agreement with experiment, we find that homogeneous mixing of SiO2 and TiO2 in bulk crystalline phases is energetically unfavourable. Conversely, we find that SiO2-TiO2 mixing is energetically favoured in small (TixSi1-xO2)n nanoclusters. Following the evolution of mixing energy with nanocluster size and composition we find that mixing is most favoured in nanoclusters with a diameter of 1 nm with TiO2 molar fractions between 0.3-0.5. Thereafter, mixed nanoclusters with increasing size have progressively less negative mixing energies up to diameters of approximately 1.5 nm. We propose some chemical-structural principles to help rationale this energetically favourable nanoscale mixing. As a guide for experimentalists to observe and characterize these mixed nano-species we also provide two measurable signatures of mixing based on their unique vibrational and structural characteristics. read less USED (low confidence) H. Liu et al., “High-thermoelectric performance of TiO2-x fabricated under high pressure at high temperatures,” Journal of Materiomics. 2017. link Times cited: 31 USED (low confidence) LiuHaixing, Lujing, ZhengTing, LiuDongmei, and CuiFuyi, “Molecular Dynamics Simulation of Natural Organic Matter–TiO2 Nanoparticle Interaction in Aqueous Environment: Effects of Ca2+ and Na+ Ions,” Environmental Engineering Science. 2017. link Times cited: 2 Abstract: This work aimed to explore the dynamic properties and mechan… read moreAbstract: This work aimed to explore the dynamic properties and mechanisms between natural organic matter and engineered nanomaterials (NOM–ENMs) interactions in aqueous solutions with the existence... read less USED (low confidence) J. Wang, L. Zhao, M. Wang, and S. Lin, “Molecular Insights into Early Nuclei and Interfacial Mismatch during Vapor Deposition of Hybrid Perovskites on Titanium Dioxide Substrate,” Crystal Growth & Design. 2017. link Times cited: 7 Abstract: Theoretical understanding of the nucleus structures of hybri… read moreAbstract: Theoretical understanding of the nucleus structures of hybrid perovskites, such as those of the prototypical methylammonium lead triiodide (MAPbI3), can greatly improve the deposited thin film quality and the resulting optoelectronic device performance. In this paper, we report a systematic molecular dynamics simulation study on nucleation and interfacial mismatch during the vapor deposition of MAPbI3 on the TiO2 substrate under different ionic precursor (PbI2 and MAI salts) compositions and temperatures. Despite significant anisotropic lattice mismatches, small defects are observed at the TiO2/[MAI]0 interface due to intermediate electrostatic attractions between I and Ti atoms, while very strong electrostatic attractions between Pb and O atoms lead to significant defects at the TiO2/[PbI2]0 interface. From the vapor deposition simulations, we identify PbI42– tetrahedra, PbI53– pyramids, and PbI64– octahedra as dominant polyhedral building blocks of early MAPbI3 nuclei. Specifically, the PbI53– pyramids ... read less USED (low confidence) E. M. Kiarii, K. Govender, P. Ndungu, and P. Govender, “The generation of charge carriers in semi conductors – A theoretical study,” Chemical Physics Letters. 2017. link Times cited: 17 USED (low confidence) X. Chen, J. Zhang, and Y.-Q. Zhao, “Molecular dynamics study of the effect of substrate temperature and Ar ion assisted deposition on the deposition of amorphous TiO2 films,” Applied Surface Science. 2017. link Times cited: 5 USED (low confidence) A. Bahramian, “Molecular interactions insights underlying temperature-dependent structure of water molecules on TiO2 nanostructured film: A computational study using reactive and non-reactive force fields,” Fluid Phase Equilibria. 2017. link Times cited: 9 USED (low confidence) O. Lamiel-García, A. Cuko, M. Calatayud, F. Illas, and S. Bromley, “Predicting size-dependent emergence of crystallinity in nanomaterials: titania nanoclusters versus nanocrystals.,” Nanoscale. 2017. link Times cited: 59 Abstract: Bottom-up and top-down derived nanoparticle structures refin… read moreAbstract: Bottom-up and top-down derived nanoparticle structures refined by accurate ab initio calculations are used to investigate the size dependent emergence of crystallinity in titania from the monomer upwards. Global optimisation and data mining are used to provide a series of (TiO2)N global minima candidates in the range N = 1-38, where our approach provides many new low energy structures for N > 10. A range of nanocrystal cuts from the anatase crystal structure are also considered up to a size of over 250 atoms. All nanocrystals considered are predicted to be metastable with respect to non-crystalline nanoclusters, which has implications with respect to the limitations of the cluster approach to modelling large titania nanosystems. Extrapolating both data sets using a generalised expansion of a top-down derived energy expression for nanoparticles, we obtain an estimate of the non-crystalline to crystalline crossover size for titania. Our results compare well with the available experimental results and imply that anatase-like crystallinity emerges in titania nanoparticles of approximately 2-3 nm diameter. read less USED (low confidence) S. Demirci, T. Dikici, M. Yurddaşkal, S. Gultekin, M. Toparli, and Çeli̇k E., “Synthesis and characterization of Ag doped TiO2 heterojunction films and their photocatalytic performances,” Applied Surface Science. 2016. link Times cited: 141 USED (low confidence) Y. Zhang et al., “Temperature-dependent structural properties of water molecules confined in TiO2 nanoslits: Insights from molecular dynamics simulations,” Fluid Phase Equilibria. 2016. link Times cited: 17 USED (low confidence) S. Liu, X. Meng, J. M. Perez-Aguilar, and R. Zhou, “An In Silico study of TiO2 nanoparticles interaction with twenty standard amino acids in aqueous solution,” Scientific Reports. 2016. link Times cited: 46 USED (low confidence) H. Lee, S. Han, R. C. Seshadri, and S. Sampath, “Thermoelectric properties of in-situ plasma spray synthesized sub-stoichiometry TiO2−x,” Scientific Reports. 2016. link Times cited: 39 USED (low confidence) Z. Futera and N. J. English, “Electric-Field Effects on Adsorbed-Water Structural and Dynamical Properties at Rutile- and Anatase-TiO2 Surfaces,” Journal of Physical Chemistry C. 2016. link Times cited: 35 Abstract: We have investigated the effects of external static electric… read moreAbstract: We have investigated the effects of external static electric fields applied to a wide variety of TiO2/water interfaces using nonequilibrium molecular-dynamics techniques. The externally applied electric fields were found to be relatively weak vis-a-vis intrinsic electric fields computed in the interfacial regions, the magnitude of which varied from 1.8 V/A toward bulklike water up to 4.5 V/A at the interface. The molecular arrangement of the first hydration layer is determined fully by the surface structure of TiO2, where water is coordinated to unsaturated titanium atoms and/or interacting with exposed surface oxygen atoms. Moreover, the water dipoles tend to align with the strong intrinsic field. As a result, diffusion of water in this region was found to be by 1 order of magnitude lower than that of bulk water; application of an external electric field did not lead to a considerable change. In contrast to unperturbed diffusivity, a rather strong response of hydrogen-bond lifetime to the applied field w... read less USED (low confidence) N. Artrith and A. Urban, “An implementation of artificial neural-network potentials for atomistic materials simulations: Performance for TiO2,” Computational Materials Science. 2016. link Times cited: 350 USED (low confidence) A. Bansal, H. Mishra, S. Bhattacharya, and B. R. Singh, “First Principles Calculations of Bonding and Charges at the Al 2 Interface in a c-Si/SiO 2 O 3 Interface in a c-Si/SiO 2 /am-Al 2 O 3 Structure Applicable for the Surface Passivation of Silicon-Based Solar Cells,” IEEE Transactions on Electron Devices. 2016. link Times cited: 9 Abstract: We present the electronic properties of the crystalline-sili… read moreAbstract: We present the electronic properties of the crystalline-silicon (c-Si)/SiO2/am-Al2O3 interface using first principles calculations. First, we generate a relaxed $3\,\times \,1$ supercell of amorphous (am)-Al2O3, which we use as a benchmark structure, validated through the experimental data. Next, using this, we generate a relaxed supercell of the c-Si/am-Al2O3 interface with a thin layer of SiO2 sandwiched between them. With this structure, we demonstrate that at the interface section, the percentage of the tetrahedral coordinated Al atoms decreases while that of the octahedral coordinated Al atoms increases compared with the Al atoms present in the bulk section of the interface structure. In addition, on an average, the effective charges on Al atoms increase by 0.19|e|, while for O atoms, the effective charges decrease by 0.02|e|. This change in the bonding distribution and charges near the interface might be responsible for the occurrence of negative fixed charges, also confirmed by various experiments involving am-Al2O3 passivation in Si-based solar cells. The origin of these negative charges on the other hand is under discussion and speculation. read less USED (low confidence) J. Lu et al., “Molecular dynamics simulations of interfacial interactions between small nanoparticles during diffusion-limited aggregation,” Applied Surface Science. 2015. link Times cited: 33 USED (low confidence) M. Turowski et al., “Practice-oriented optical thin film growth simulation via multiple scale approach,” Thin Solid Films. 2015. link Times cited: 20 USED (low confidence) S. Zhu, S.-H. Xie, and Z. Liu, “Nature of Rutile Nuclei in Anatase-to-Rutile Phase Transition.,” Journal of the American Chemical Society. 2015. link Times cited: 90 Abstract: The solid phase transition of TiO2, in particular anatase to… read moreAbstract: The solid phase transition of TiO2, in particular anatase to rutile, has been extensively studied in the past 30 years. To seek the nucleation site at the beginning of phase transition is highly challenging, which asks for new theoretical techniques with high spatial and temporal resolution. This work reports the first evidence on the atomic structure of the nucleation sites in the TiO2 anatase-to-rutile phase transition. Novel automated theoretical methods, namely stochastic surface walking based pathway sampling methods, are utilized to resolve the lowest energy pathways at the initial stage of phase transition. We show that among common anatase surfaces, only the (112) ridged surface provides the nucleation site for phase transition, which can lead to the formation of both TiO2-II and brookite thin slabs. The TiO2-II phase is kinetically preferred product; the propagation into the subsurface is still hindered by high barriers that is the origin for the slow kinetics of nuclei formation. The rutile nuclei are thus not rutile phase but nascent metastable TiO2-II phase in an anatase matrix. The phase transition kinetics is found to be sensitive to the compressive strain and the crystallographic directions. The results rationalize the size and morphology dependence of the anisotropic phase transition kinetics of anatase particles and could facilitate the rational design of material via controlled solid phase transition. read less USED (low confidence) X.-tong Chen et al., “Molecular dynamics study of the effect of titanium ion energy on surface structure during the amorphous TiO2 films deposition,” Applied Surface Science. 2015. link Times cited: 6 USED (low confidence) H. Pham and L.-wang Wang, “Electronic structures and current conductivities of B, C, N and F defects in amorphous titanium dioxide.,” Physical chemistry chemical physics : PCCP. 2015. link Times cited: 19 Abstract: Although titanium dioxide (TiO2) has been extensively studie… read moreAbstract: Although titanium dioxide (TiO2) has been extensively studied and widely used in energy and environmental areas, the amorphous form and its related defect properties are poorly understood. Recent studies, however, have emphasized the crucial role of amorphousness in producing competitively good performances in photochemical applications. In this work we have investigated for the first time the effects of various dopants (B, C, N and F) on charge carrier transport in amorphous titanium dioxide (a-TiO2), given that doping is a common technique used to tune the electronic properties of semiconductors, and that the existence of these impurities could also be unintentionally introduced during the synthesis process. The a-TiO2 model was obtained using a classical molecular dynamics method, followed by density-functional theory calculations (DFT + U, with Hubbard correction term U) on electronic structures and defect states. The formation of these impurity defects in a-TiO2 was found to be energetically more favorable by several eV than their crystal counterparts (in rutile). The contributions of these defect states to the charge transfer processes were examined by means of Marcus theory. read less USED (low confidence) J. Li, N. Yu, H. Jiang, J. Leng, and H. Geng, “Effects of annealing temperature on dealloying of Ti–Cu Alloy,” Corrosion Science. 2015. link Times cited: 17 USED (low confidence) J. C. Garcia, M. Nolan, and N. Deskins, “The nature of interfaces and charge trapping sites in photocatalytic mixed-phase TiO2 from first principles modeling.,” The Journal of chemical physics. 2015. link Times cited: 35 Abstract: Mixed phase rutile/anatase catalysts show increased reactivi… read moreAbstract: Mixed phase rutile/anatase catalysts show increased reactivity compared with the pure phases alone. However, the mechanism causing this effect is not fully understood. The electronic properties of the interface and the relative energy of the electron in each phase play a key role in lowering the rate of recombination of electron hole pairs. Using density functional theory and the +U correction, we calculated the bands offsets between the phases taking into account the effect of the interface. Our model included several thousands atoms, and thus is a good representation of an interface between actual nanoparticles. We found rutile to have both higher conduction and valence band offsets than rutile, leading to an accumulation of electrons in the anatase phase accompanied by hole accumulation in the rutile phase. We also probed the electronic structure of our heterostructure and found a gap state caused by electrons localized in undercoordinated Ti atoms which were present within the interfacial region. Interfaces between bulk materials and between exposed surfaces both showed electron trapping at undercoordinated sites. These undercoordinated (typically four) atoms present localized electrons that could enable reduction reactions in the interfacial region, and could explain the increased reactivity of mixed-phase TiO2 photocatalyst materials. read less USED (low confidence) H. Pham and L.-wang Wang, “Oxygen vacancy and hole conduction in amorphous TiO2.,” Physical chemistry chemical physics : PCCP. 2015. link Times cited: 157 Abstract: The amorphous titanium dioxide (a-TiO2) has drawn attention … read moreAbstract: The amorphous titanium dioxide (a-TiO2) has drawn attention recently due to the finding that it holds promise for coating conventional photoelectrodes for corrosion protection while still allowing the holes to transport to the surface. The mechanism of hole conductivity at a level much higher than the edge of the valence band is still a mystery. In this work, an amorphous TiO2 model is obtained from molecular dynamics employing the "melt-and-quench" technique. The electronic properties, polaronic states and the hole conduction mechanism in amorphous structure were investigated by means of density functional theory with Hubbard's energy correction (DFT + U) and compared to those in crystalline (rutile) TiO2. The formation energy of the oxygen vacancy was found to reduce significantly (by a few eV) upon amorphization. Our theoretical study suggested that the oxygen vacancies and their defect states provide hopping channels, which are comparable to experimental observations and could be responsible for hole conduction in the "leaky" TiO2 recently discovered for the photochemical water-splitting applications. read less USED (low confidence) I. Gonzalo-Juan, A. Krejci, M. A. Rodríguez, Y. Zhou, K. Fichthorn, and J. Dickerson, “Dipole moment-tuned packing of TiO2 nanocrystals into monolayer films by electrophoretic deposition,” Applied Physics Letters. 2014. link Times cited: 9 Abstract: The magnitude of the electric dipole moment of TiO2 nanocrys… read moreAbstract: The magnitude of the electric dipole moment of TiO2 nanocrystals was tuned as a function of the shape of the nanocrystal to facilitate the formation of tightly-packed monolayers, fabricated by electrophoretic deposition. The dipole moment aided the formation of monolayers with quasi-hexagonal ordering. Voronoi tessellation analysis confirmed that nanorods facilitated higher degrees of order than nanospheres. Thermal and dilatometric analyses demonstrate that the nanocrystals' sintering temperature was reduced below 1250 °C—a useful development for device applications. read less USED (low confidence) M. Robinson, N. Marks, and G. Lumpkin, “Structural dependence of threshold displacement energies in rutile, anatase and brookite TiO2,” Materials Chemistry and Physics. 2014. link Times cited: 28 USED (low confidence) M. Chen, T. Zheng, C. Wu, and C.-M. Xing, “Molecular dynamics simulations of collagen adsorption onto grooved rutile surface: the effects of groove width.,” Colloids and surfaces. B, Biointerfaces. 2014. link Times cited: 12 USED (low confidence) H. Zhang and J. Banfield, “Structural characteristics and mechanical and thermodynamic properties of nanocrystalline TiO2.,” Chemical reviews. 2014. link Times cited: 258 USED (low confidence) G. Müller et al., “Poly (hexamethylene biguanide) adsorption on hydrogen peroxide treated Ti-Al-V alloys and effects on wettability, antimicrobial efficacy, and cytotoxicity.,” Biomaterials. 2014. link Times cited: 28 USED (low confidence) A. Bandura, R. Evarestov, and S. I. Lukyanov, “Structure reconstruction of TiO2-based multi-wall nanotubes: first-principles calculations.,” Physical chemistry chemical physics : PCCP. 2014. link Times cited: 19 Abstract: A new method of theoretical modelling of polyhedral single-w… read moreAbstract: A new method of theoretical modelling of polyhedral single-walled nanotubes based on the consolidation of walls in the rolled-up multi-walled nanotubes is proposed. Molecular mechanics and ab initio quantum mechanics methods are applied to investigate the merging of walls in nanotubes constructed from the different phases of titania. The combination of two methods allows us to simulate the structures which are difficult to find only by ab initio calculations. For nanotube folding we have used (1) the 3-plane fluorite TiO2 layer; (2) the anatase (101) 6-plane layer; (3) the rutile (110) 6-plane layer; and (4) the 6-plane layer with lepidocrocite morphology. The symmetry of the resulting single-walled nanotubes is significantly lower than the symmetry of initial coaxial cylindrical double- or triple-walled nanotubes. These merged nanotubes acquire higher stability in comparison with the initial multi-walled nanotubes. The wall thickness of the merged nanotubes exceeds 1 nm and approaches the corresponding parameter of the experimental patterns. The present investigation demonstrates that the merged nanotubes can integrate the two different crystalline phases in one and the same wall structure. read less USED (low confidence) R. Darkins, M. Sushko, J. Liu, and D. Duffy, “Stress in titania nanoparticles: an atomistic study.,” Physical chemistry chemical physics : PCCP. 2014. link Times cited: 17 Abstract: Stress engineering is becoming an increasingly important met… read moreAbstract: Stress engineering is becoming an increasingly important method for controlling electronic, optical, and magnetic properties of nanostructures, although the concept of stress is poorly defined at the nanoscale. We outline a procedure for computing bulk and surface stress in nanoparticles using atomistic simulation. The method is applicable to ionic and non-ionic materials alike and may be extended to other nanostructures. We apply it to spherical anatase nanoparticles ranging from 2 to 6 nm in diameter and obtain a surface stress of 0.89 N m(-1), in agreement with experimental measurements. Based on the extent that stress inhomogeneities at the surface are transmitted into the bulk, two characteristic length-scales are identified: below 3 nm bulk and surface regions cannot be defined and the available analytic theories for stress are not applicable, and above about 5 nm the stress becomes well-described by the theoretical Young-Laplace equation. The effect of a net surface charge on the bulk stress is also investigated. It is found that moderate surface charges can induce significant bulk stresses, on the order of 100 MPa, in nanoparticles within this size range. read less USED (low confidence) G. Dolgonos, “Self-consistent-charge density-functional tight-binding molecular dynamics simulations of amorphous TiO2 growth,” Surface Science. 2014. link Times cited: 7 USED (low confidence) C. Yang, C. Peng, D. Zhao, C. Liao, J. Zhou, and X. Lu, “Molecular simulations of myoglobin adsorbed on rutile (1 1 0) and (0 0 1) surfaces,” Fluid Phase Equilibria. 2014. link Times cited: 18 USED (low confidence) W. Friedrichs, S. Köppen, and W. Langel, “Titanium binding dodecapeptides and the impact of water structure,” Surface Science. 2013. link Times cited: 17 USED (low confidence) A. Bahramian, “Study on growth rate of TiO2 nanostructured thin films: simulation by molecular dynamics approach and modeling by artificial neural network,” Surface and Interface Analysis. 2013. link Times cited: 22 Abstract: Effects of the deposition process parameters on the thicknes… read moreAbstract: Effects of the deposition process parameters on the thickness of TiO2 nanostructured film were simulated using the molecular dynamics (MD) approach and modeled by the artificial neural network (ANN) and regression method. Accordingly, TiO2 nanostructured film was prepared experimentally with the sol–gel dip‐coating method. Structural instabilities can be expected, due to short‐ and/or long‐range intermolecular forces, leading to the surface inhomogeneities. In the MD simulation, the Morse potential function was used for the inter‐atomic interactions, and equations of motion for atoms were solved by Verlet algorithm. The effect of the withdrawal velocity, drying temperature and number of deposited layers were studied in order to characterize the film thickness. The results of MD simulations are reasonably consistent with atomic force microscopy, scanning electron microscopy and Dektak surface profiler. Finally, the outputs from experimental data were analyzed by using the ANN in order to investigate the effects of deposition process parameters on the film thickness. In this case, various architectures have been checked using 75% of experimental data for training of the ANN. Among the various architectures, feed‐forward back‐propagation network with trainer training algorithm was found as the best architecture. Based on the R‐squared value, the ANN is better than the regression model in predicting the film thickness. The statistical analysis for those results was then used to verify the fitness of the complex process model. Based on the results, this modeling methodology can explain the characteristics of the TiO2 nanostructured thin film and growth mechanism varying with process conditions. © 2013 The Authors. Surface and Interface Analysis published by John Wiley & Sons Ltd. read less USED (low confidence) R. Eithiraj and K. Geethalakshmi, “Suitability of amorphous TiO2 nanoparticles as a photoelectrode in dye sensitized solar cells: A DFT–TDDFT study,” Chemical Physics Letters. 2013. link Times cited: 15 USED (low confidence) T. Zheng, C. Wu, and M. Chen, “Early adsorption of collagen on the reduced rutile (110) surface mediated by water: A molecular dynamics study,” Surface Science. 2013. link Times cited: 10 USED (low confidence) C. Cheng, C. Shih, R. Behera, and W.-D. Hsu, “Investigation of initial stages of nano-ceramic particle sintering using atomistic simulations,” Surface & Coatings Technology. 2013. link Times cited: 5 USED (low confidence) K. Ghuman, N. Goyal, and S. Prakash, “Vibrational density of states of TiO2 nanoparticles,” Journal of Non-crystalline Solids. 2013. link Times cited: 6 USED (low confidence) N. A. Marks et al., “Chemical evolution via beta decay: a case study in strontium-90,” Journal of Physics: Condensed Matter. 2013. link Times cited: 18 Abstract: Using 90Sr as a representative isotope, we present a framewo… read moreAbstract: Using 90Sr as a representative isotope, we present a framework for understanding beta decay within the solid state. We quantify three key physical and chemical principles, namely momentum-induced recoil during the decay event, defect creation due to physical displacement, and chemical evolution over time. A fourth effect, that of electronic excitation, is also discussed, but this is difficult to quantify and is strongly material dependent. The analysis is presented for the specific cases of SrTiO3 and SrH2. By comparing the recoil energy with available threshold displacement data we show that in many beta-decay situations defects such as Frenkel pairs will not be created during decay as the energy transfer is too low. This observation leads to the concept of chemical evolution over time, which we quantify using density functional theory. Using a combination of Bader analysis, phonon calculations and cohesive energy calculations, we show that beta decay leads to counter-intuitive behavior that has implications for nuclear waste storage and novel materials design. read less USED (low confidence) R. Kavathekar, N. J. English, and J. MacElroy, “Spatial distribution of adsorbed water layers at the TiO2 rutile and anatase interfaces,” Chemical Physics Letters. 2012. link Times cited: 26 USED (low confidence) M. Wei, L. Zhang, L. Lu, Y. Zhu, K. Gubbins, and X. Lu, “Molecular behavior of water in TiO2 nano-slits with varying coverages of carbon: a molecular dynamics simulation study.,” Physical chemistry chemical physics : PCCP. 2012. link Times cited: 36 Abstract: It is well known that titanium dioxide (TiO(2)) is biocompat… read moreAbstract: It is well known that titanium dioxide (TiO(2)) is biocompatible and environmentally friendly. Consequently, TiO(2) is widely applied in many fields, such as implant materials, photocatalysis, pigments, cosmetic additives, etc. Mesoporous TiO(2) finds many industrial applications, because of its high surface area and stable structure. However, the strong interaction between TiO(2) and water molecules sometimes limits its application to solution environments. Our previous computational work showed that changes to the surface chemistry of TiO(2) can affect the hydrogen bond network of water molecules on the TiO(2) surface, and so influence the diffusion of water in the slits. Thus, a carbon-modified TiO(2) surface could be an alternative way to avoid this limitation. In this work, a slit pore model with a modified TiO(2) surface (pore widths 1.2 nm, 1.6 nm and 2.0 nm) with varying carbon coverages (0%, 7%, 47%, 53%, 93% and 100%) was presented. Molecular dynamics (MD) simulations were then performed to investigate the sorption and diffusion of water in these slits. Simulation results showed that the interfacial water molecules on bare TiO(2) regions were little affected by the neighboring carbon, and they have the same properties as those on bare TiO(2) surfaces. However, the diffusion of water molecules in the center of the slit was enhanced on increase of carbon coverage, because the carbon layer broke the hydrogen bond network between the interfacial water molecules and those on the bare TiO(2) surface. It was found that in the slits (>1.2 nm) fully covered by carbon the diffusion coefficients of water are larger than that of bulk water. Moreover, large pore sizes caused an increase in the mobility of water molecules in carbon-modified TiO(2), in agreement with previous experimental work. read less USED (low confidence) M. Robinson, N. Marks, and G. Lumpkin, “Sensitivity of the threshold displacement energy to temperature and time,” Physical Review B. 2012. link Times cited: 19 Abstract: Developing a fundamental understanding of radiation dam-age … read moreAbstract: Developing a fundamental understanding of radiation dam-age is key to the development of current and future materialsfor nuclear applications. The response of a given material toirradiation is dependent on a multitude of atomic processesoccurringonthenanoscale.Thecoalescenceoftheseprocessesproduce macroscopic changes in structural and chemicalpropertiesimpactingtheintendedfunctionalityofthematerial.One of the fundamental quantities that helps define amaterials radiation tolerance is the threshold displacementenergy read less USED (low confidence) A. Mashreghi, “Determining the volume thermal expansion coefficient of TiO2 nanoparticle by molecular dynamics simulation,” Computational Materials Science. 2012. link Times cited: 15 USED (low confidence) C. Negre, V. Fuertes, M. Oviedo, F. Oliva, and C. Sánchez, “Quantum Dynamics of Light-Induced Charge Injection in a Model Dye–Nanoparticle Complex,” Journal of Physical Chemistry C. 2012. link Times cited: 51 Abstract: We present a detailed description of the direct charge injec… read moreAbstract: We present a detailed description of the direct charge injection mechanism in a coupled dye–TiO2 nanoparticle (NP) using a full quantum dynamical simulation framework. The method employed here is based on a time-dependent tight-binding model to describe the system under nonequilibrium conditions. By using this tool, we performed a simulation showing a full time-dependent picture of the photoabsorption process in type-II dye-sensitized solar cells (direct charge injection mechanism from the dye to the TiO2 NP). This task is accomplished by tuning the frequency of an applied sinusoidal time-dependent electric field with the frequency of the dye–TiO2 NP’s main absorption peak. We find that during the field irradiation there is a net charge transfer from the dye to the NP superposed with a typical charge oscillation due to absorption of radiant energy. read less USED (low confidence) B. Buesser and S. Pratsinis, “Design of nanomaterial synthesis by aerosol processes.,” Annual review of chemical and biomolecular engineering. 2012. link Times cited: 139 Abstract: Aerosol synthesis of materials is a vibrant field of particl… read moreAbstract: Aerosol synthesis of materials is a vibrant field of particle technology and chemical reaction engineering. Examples include the manufacture of carbon blacks, fumed SiO(2), pigmentary TiO(2), ZnO vulcanizing catalysts, filamentary Ni, and optical fibers, materials that impact transportation, construction, pharmaceuticals, energy, and communications. Parallel to this, development of novel, scalable aerosol processes has enabled synthesis of new functional nanomaterials (e.g., catalysts, biomaterials, electroceramics) and devices (e.g., gas sensors). This review provides an access point for engineers to the multiscale design of aerosol reactors for the synthesis of nanomaterials using continuum, mesoscale, molecular dynamics, and quantum mechanics models spanning 10 and 15 orders of magnitude in length and time, respectively. Key design features are the rapid chemistry; the high particle concentrations but low volume fractions; the attainment of a self-preserving particle size distribution by coagulation; the ratio of the characteristic times of coagulation and sintering, which controls the extent of particle aggregation; and the narrowing of the aggregate primary particle size distribution by sintering. read less USED (low confidence) K. Trachenko, E. Zarkadoula, I. Todorov, M. Dove, D. Dunstan, and K. Nordlund, “Modeling high-energy radiation damage in nuclear and fusion applications,” Nuclear Instruments & Methods in Physics Research Section B-beam Interactions With Materials and Atoms. 2012. link Times cited: 25 USED (low confidence) Y. Zhou and K. Fichthorn, “Microscopic View of Nucleation in the Anatase-to-Rutile Transformation,” Journal of Physical Chemistry C. 2012. link Times cited: 49 Abstract: We use molecular simulation techniques to investigate the an… read moreAbstract: We use molecular simulation techniques to investigate the anatase-to-rutile transformation in TiO2 nanocrystals. A thermodynamic analysis indicates that edge and corner atoms significantly influence the critical size at which rutile nanocrystals become energetically preferred over anatase. We use molecular dynamics simulations to probe kinetics of the transformation in individual anatase nanocrystals as well as in nanocrystal aggregates. We follow structural evolution using simulated X-ray diffraction. Additionally, we develop a local order parameter to distinguish individual Ti ions as anatase, rutile, or anatase {112} twin-like. We apply our local order parameter to track the formation and growth of rutile nuclei. Anatase {112} twins form easily at surfaces and interfaces of nanocrystal aggregates, and we observe that rutile forms among the twins. Stable rutile nuclei maintain {101} facets during growth as a result of nucleation from layers of alternating anatase {112} twins. Our results are in agreemen... read less USED (low confidence) M. Robinson, N. Marks, K. Whittle, and G. Lumpkin, “Systematic calculation of threshold displacement energies: Case study in rutile,” Physical Review B. 2012. link Times cited: 48 Abstract: A generalized and systematic method of calculating threshold… read moreAbstract: A generalized and systematic method of calculating threshold displacement energies (Ed ) using molecular dynamics simulations has been developed and applied to rutile TiO2. Statistically representative results have been achieved through fine sampling of impact energy and trajectory for each atomic species. Each impact trajectory is drawn from a uniform distribution of points on a unit sphere, along which, primary knock-on atoms (PKAs) with kinetic energies in the range of 20–200 eV were introduced into lattices equilibrated to 300 K. Various definitions of Ed are explored, with values presented as probabilities of defect formation. Results for the Ti PKA agree well with experimental data with a value of Ed at around 69 eV. Simulations of O PKAs contrast greatly with Ti PKAs, with displacements occurring at significantly lower energies, resulting in an O value of Ed at 19 eV. Analysis shows that replacement chains on the O sublattice are a common feature and play a significantrole in governing defect formation in rutile. read less USED (low confidence) M. Alimohammadi and K. Fichthorn, “A Force Field for the Interaction of Water with TiO2 Surfaces,” Journal of Physical Chemistry C. 2011. link Times cited: 30 Abstract: We develop a force field for the interaction of molecularly … read moreAbstract: We develop a force field for the interaction of molecularly and dissociatively adsorbed water with surfaces of TiO2 by modifying the potential proposed by Bandura and Kubicki (J. Phys. Chem.2003, 107, 11072). We test the force field by computing binding energies and conformations for molecular adsorption on the (101) and (112) surfaces of anatase and the (110) surface of rutile and dissociative adsorption on the bulk-terminated (001) surface of anatase and the (110) surface of rutile for various water surface coverages. These quantities exhibit good agreement with results from first-principles density functional theory and experiment. We use molecular dynamics (MD) simulations to obtain density profiles and statistics of hydrogen bonding for water monolayers and bilayers adsorbed on anatase (101) and these results are in good agreement with ab initio MD. The potential is suitable for large-scale MD simulations of TiO2 in aqueous environments. read less USED (low confidence) B. Uberuaga and X. Bai, “Defects in rutile and anatase polymorphs of TiO2: kinetics and thermodynamics near grain boundaries,” Journal of Physics: Condensed Matter. 2011. link Times cited: 64 Abstract: The direct consequence of irradiation on a material is the c… read moreAbstract: The direct consequence of irradiation on a material is the creation of point defects—typically interstitials and vacancies, and their aggregates—but it is the ultimate fate of these defects that determines the material’s radiation tolerance. Thus, understanding how defects migrate and interact with sinks, such as grain boundaries, is crucial for predicting the evolution of the material. We examine defect properties in two polymorphs of TiO2—rutile and anatase—to determine how these materials might respond differently to irradiation. Using molecular statics and temperature accelerated dynamics, we focus on two issues: how point defects interact with a representative grain boundary and how they migrate in the bulk phase. We find that grain boundaries in both polymorphs are strong sinks for all point defects, though somewhat stronger in rutile than anatase. Further, the defect kinetics are very different in the two polymorphs, with interstitial species diffusing quickly in rutile while oxygen defects—both interstitials and vacancies—are fast diffusers in anatase. These results allow us to speculate on how grain boundaries will modify the radiation tolerance of these materials. In particular, grain boundaries in rutile will lead to a space charge layer at the boundary and a vacancy-rich damage structure, while in anatase the damage structure would likely be more stoichiometric, but with larger defects consisting primarily of Ti ions. read less USED (low confidence) S. Murphy, P. Zeller, A. Chartier, and L. Brutzel, “Atomistic Simulation of the Structural, Thermodynamic, and Elastic Properties of Li2TiO3,” Journal of Physical Chemistry C. 2011. link Times cited: 34 Abstract: Lithium-based ceramics, such as lithium metatitanate, have b… read moreAbstract: Lithium-based ceramics, such as lithium metatitanate, have been proposed for adoption in the breeder blanket region of a fusion reactor. In this article, we report a combination of empirical and density functional theory (DFT) simulations employing “on-the-fly” pseudopotentials for Li2TiO3. The smoothing parameters of the plane-wave pseudopotentials were optimized to ensure an appropriate level of precision for determination of structural, thermodynamic, and elastic properties. As the elastic properties of lithium metatitanate are not well-known, the efficacy of the DFT simulations employing the new pseudopotentials was explored using Li2O and TiO2 where experimental data are available. These pseudopotentials are then used to investigate the three intermediate temperature phases of Li2TiO3 (i.e., C2/c, C2/m, and P3112). Finally, we examine the elastic properties of Li2TiO3 using both DFT and an empirical potential model and find it to be, irrespective of space group, more resistant to deformation than oth... read less USED (low confidence) T. Köhler, G. Dolgonos, and T. Frauenheim, “Atomistische Simulation von amorphen TiO2‐Strukturen für optische Schichtsysteme,” Vakuum in Forschung und Praxis. 2011. link Times cited: 1 Abstract: Zielsetzung des vorliegenden Beitrages ist es, einen kurzen … read moreAbstract: Zielsetzung des vorliegenden Beitrages ist es, einen kurzen Überblick über die Möglichkeiten der Modellierung oxidischer optischer Materialien, am Beispiel des amorphen Titanoxids (TiO2), zu geben. Im Vordergrund steht hierbei ein effizientes approximatives Dichtefunktional‐basiertes Verfahren (DFTB), mit dem es möglich ist, Einsicht in lokale Struktur‐Eigenschaftsbeziehungen auf atomarer Basis zu bekommen. Perspektivisch werden Wege aufgezeigt, die Erkenntnisse auf andere Problemklassen, z. B. Grenzflächen zu übertragen, deren Optimierung größerskalige Betrachtungen erfordern. Die Studien sind im Rahmen des PLuTO‐Pilotprojektes zur Plasmaabscheidung optischer Schichtsysteme eingebettet. read less USED (low confidence) K. Kaur, S. Prakash, N. Goyal, R. Singh, and P. Entel, “Structure factor of amorphous TiO 2 nanoparticle; Molecular Dynamics Study,” Journal of Non-crystalline Solids. 2011. link Times cited: 17 USED (low confidence) O. Stenzel et al., “Plasma and optical thin film technologies,” Optical Systems Design. 2011. link Times cited: 7 Abstract: The PluTO project is aimed at combining thin-film and plasma… read moreAbstract: The PluTO project is aimed at combining thin-film and plasma technologies. Accordingly, the consortium comprises experts in optical coating (Laser Zentrum Hannover, Fraunhofer IOF) and such in plasma technology (INP Greifswald, Ruhr University of Bochum RUB). The process plasmas available, especially the sheath layers, will be thoroughly characterized by means of special probes, so that the types, numbers and energies of the particles participating in the coating formation processes can be determined comprehensively in every detail for the first time. The data thus obtained will provide a basis for a numerical modelling of layer growth at atomic scale (Bremen Center for Computational Materials Science BCCMS). The results are expected to deepen the understanding of the physical mechanisms responsible for the influence of plasma action on the layer properties. In parallel, suitable tools for process monitoring will be identified and made available. Some first results have already been achieved which prove the viability of the approach. read less USED (low confidence) R. Kavathekar, P. Dev, N. J. English, and J. MacElroy, “Molecular dynamics study of water in contact with the TiO2 rutile-110, 100, 101, 001 and anatase-101, 001 surface,” Molecular Physics. 2011. link Times cited: 80 Abstract: We have carried out classical molecular dynamics of various … read moreAbstract: We have carried out classical molecular dynamics of various surfaces of TiO2 with its interface with water. We report the geometrical features of the first and second monolayers of water using a Matsui Akaogi (MA) force field for the TiO2 surface and a flexible single point charge model for the water molecules. We show that the MA force field can be applied to surfaces other than rutile (110). It was found that water OH bond lengths, H–O–H bond angles and dipole moments do not vary due to the nature of the surface. However, their orientation within the first and second monolayers suggest that planar rutile (001) and anatase (001) surfaces may play an important role in not hindering removal of the products formed on these surfaces. Also, we discuss the effect of surface termination in order to explain the layering of water molecules throughout the simulation box. read less USED (low confidence) B. Buesser, A. Gröhn, and S. Pratsinis, “Sintering Rate and Mechanism of TiO2 Nanoparticles by Molecular Dynamics.,” The journal of physical chemistry. C, Nanomaterials and interfaces. 2011. link Times cited: 119 Abstract: Titania is the dominant white pigment and photocatalytic mat… read moreAbstract: Titania is the dominant white pigment and photocatalytic material, a key component of sunscreens and has promising applications in photovoltaics and sensors of organic vapors. The growth of TiO2 nanoparticles by sintering, the critical step during their large scale manufacture and processing, is elucidated and quantified by molecular dynamics. Highly mobile ions from the particle surface fill in the initially concave space between nanoparticles (surface diffusion) forming the final, fully-coalesced, spherical-like particle with minimal displacement of inner Ti and O ions (grain boundary diffusion) revealing also the significance and sequence of these two sintering mechanisms of TiO2. A sintering rate for TiO2 nanoparticles is extracted that is much faster than that in the literature but nicely converges to it for increasing particle size. read less USED (low confidence) A. Hallil, É. Amzallag, S. Landron, and R. Tétot, “Properties of rutile TiO2 surfaces from a Tight-Binding Variable-Charge model. Comparison with ab initio calculations,” Surface Science. 2011. link Times cited: 21 USED (low confidence) M. Wei et al., “Diffusion of water molecules confined in slits of rutile TiO2(110) and graphite(0001),” Fluid Phase Equilibria. 2011. link Times cited: 60 USED (low confidence) M. Vijayakumar et al., “Lithium diffusion in Li4Ti5O12 at high temperatures,” Journal of Power Sources. 2011. link Times cited: 60 USED (low confidence) M. Akindeju, V. Pareek, M. Tadé, and A. Rohl, “A NOVEL SPINNING DISC CONTINUOUS STIR TANK AND SETTLER REACTOR (SDCSTR) MODEL FOR CONTINUOUS SYNTHESIS OF TITANIA: A PHENOMENOLOGICAL MODEL,” Chemical Engineering Communications. 2010. link Times cited: 5 Abstract: A novel phenomenological spinning disc continuous stir tank … read moreAbstract: A novel phenomenological spinning disc continuous stir tank and settler reactor (SDCSTR) has been modeled for continuous synthesis of titania from its chloride precursor and water in which the desired polymorph, particle size, and distribution are controlled by the characteristics of the atomized inlet reagents, disc, and tank stir rate. This energy-efficient reactor generates seeding nuclei in the aerosol reacting volume that are then deployed for heterogeneous nucleation and particle growth in the metastable reacting volume of the aqueous (sol) process. Once at steady state, the enhanced TiO2 nanoparticles due to the OH−–H+ chemisorbed on the surface (with surface energy 0.5 < σ < 2.11 N/m) are continuously withdrawn at a rate equivalent to the particle settling rate from the settler. This reactor model eliminates the energy intensity required in traditional chemical vapor deposition (CVD) and aerosol reactors and provides better control for particle growth and size distribution by increasing particle residence time in the metastable zone of the aqueous (sol) reaction stage. read less USED (low confidence) L. Vernon, S. Kenny, and R. Smith, “Growth of TiO2 surfaces following low energy (<40 eV) atom and small cluster bombardment,” Nuclear Instruments & Methods in Physics Research Section B-beam Interactions With Materials and Atoms. 2010. link Times cited: 12 USED (low confidence) J. Schneider and L. Ciacchi, “First principles and classical modeling of the oxidized titanium (0001) surface,” Surface Science. 2010. link Times cited: 35 USED (low confidence) R. R. Maphanga, S. C. Parker, and P. Ngoepe, “Atomistic simulation of the surface structure of electrolytic manganese dioxide,” Surface Science. 2009. link Times cited: 34 USED (low confidence) S. Hamad, J. Sánchez-Valencia, Á. Barranco, J. A. Mejías, and A. Gonzalez-Elipe, “Molecular dynamics simulation of the effect of pH on the adsorption of rhodamine laser dyes on TiO2 hydroxylated surfaces,” Molecular Simulation. 2009. link Times cited: 13 Abstract: We have carried out a study of adsorption, on the (1 0 1) su… read moreAbstract: We have carried out a study of adsorption, on the (1 0 1) surface of anatase TiO2, of two industrially relevant rhodamine molecules [rhodamine 6G (R6G) and rhodamine 800 (R800)] employing molecular dynamics. These theoretical studies have shown that R6G must adsorb on surfaces under basic conditions. Moreover, the adsorption of this molecule shows a strong dependence upon the pH of the system, i.e. under basic conditions the adsorption energy is quite high, under neutral conditions the adsorption energy is lower and under acidic conditions an even lower adsorption energy indicates that there must be very little adsorption under such conditions. By contrast, for R800, there is little dependence of the adsorption energy upon the pH, suggesting that the amount of adsorption of these molecules is little affected by this parameter. These theoretical results are in qualitative agreement with the experimental results consisting of the incorporation of these dye molecules into porous thin films. read less USED (low confidence) D. Song, Y. Liang, M. Chen, and Q. Bai, “Molecular dynamics study on surface structure and surface energy of rutile TiO2 (1 1 0),” Applied Surface Science. 2009. link Times cited: 22 USED (low confidence) S. Woodley and C. Catlow, “Structure prediction of titania phases : Implementation of Darwinian versus Lamarckian concepts in an Evolutionary Algorithm,” Computational Materials Science. 2009. link Times cited: 49 USED (low confidence) H. Zhang, B. Chen, J. Banfield, and G. Waychunas, “Atomic structure of nanometer-sized amorphous TiO2,” Physical Review B. 2008. link Times cited: 152 Abstract: Amorphous titania $({\text{TiO}}_{2})$ is an important precu… read moreAbstract: Amorphous titania $({\text{TiO}}_{2})$ is an important precursor for synthesis of single-phase nanocrystalline anatase. We synthesized amorphous titania by hydrolysis of titanium ethoxide at the ice point. Transmission electron microscopy examination and nitrogen gas adsorption indicated that the particle size of the synthesized titania is $\ensuremath{\sim}2\text{ }\text{nm}$. Synchrotron wide-angle x-ray scattering (WAXS) was used to probe the atomic correlations in this amorphous sample. Atomic pair-distribution function (PDF) derived from Fourier transform of the WAXS data was used for reverse Monte Carlo (RMC) simulations of the atomic structure of the amorphous ${\text{TiO}}_{2}$ nanoparticles. Molecular-dynamics simulations were used to generate input structures for the RMC. X-ray-absorption spectroscopy (XAS) simulations were used to screen candidate structures obtained from the RMC by comparing with experimental XAS data. The structure model that best describes both the WAXS and XAS data shows that amorphous ${\text{TiO}}_{2}$ particles consist of a highly distorted shell and a small strained anataselike crystalline core. The average coordination number of Ti is 5.3 and most Ti-O bonds are populated around $1.940\text{ }\text{\AA{}}$. Relative to bulk ${\text{TiO}}_{2}$, the reduction in the coordination number is primarily due to the truncation of the Ti-O octahedra at the amorphous nanoparticle surface and the shortening of the Ti-O bond length to the bond contraction in the distorted shell. The pre-existence of the anataselike core may be critical to the formation of single-phase nanocrystalline anatase in crystallization of amorphous ${\text{TiO}}_{2}$ upon heating. read less USED (low confidence) V. Kopardé and P. Cummings, “Phase transformations during sintering of titania nanoparticles.,” ACS nano. 2008. link Times cited: 98 Abstract: The size below which anatase nanoparticles become more stabl… read moreAbstract: The size below which anatase nanoparticles become more stable than rutile nanoparticles (crossover diameter) is dependent on the environment of the nanoparticles. It is smaller for nanoparticles in vacuum than those in water and continues to decrease with increase in temperature. Phase transformation between anatase and rutile phases is facilitated by enhanced ionic mobility at temperatures near the melting point of the nanoparticles. Multiparticle multiphase molecular dynamics simulations of TiO(2) nanoparticles undergoing sintering-induced phase transformations are reported here. Over the time scales accessible to molecular dynamics simulations, we found that the final sintering agglomerate transformed to the rutile phase, provided one of the sintering nanoparticles was rutile, while sintering of anatase and amorphous nanoparticles resulted in a brookite agglomerate. No such phase transformations were observed at temperatures away from nanoparticle's melting temperatures. read less USED (low confidence) G. Lumpkin et al., “Experimental and atomistic modeling study of ion irradiation damage in thin crystals of theTiO2polymorphs,” Physical Review B. 2008. link Times cited: 37 USED (low confidence) P. Tian, “Molecular dynamics simulations of nanoparticles.” 2008. link Times cited: 37 Abstract: A review of molecular dynamics simulation studies of nanopar… read moreAbstract: A review of molecular dynamics simulation studies of nanoparticles is presented. While research on nanoparticles and their usage in industries, healthcare, and biomedical sciences has been very active, real time observation and analysis of some dynamical and thermodynamic properties and physical mechanisms underlying many of the special characteristics of various nanoparticles are not easily achieved experimentally. Due to the rapid development of the computational algorithms and available computational resources to scientific researchers and relatively small sizes of nanoparticles, molecular dynamics (MD) simulations, together with other computational methods, occupy an increasingly important niche in this rapidly developing and expanding field. As part of the Annual Reports, the focus of this review is on the research published during the last year. A brief survey of fundamentals of MD simulations is given first, followed by how various MD methodologies are utilized for the investigations of the nucleation and melting behavior of various metallic nanoparticles, for the understanding of structural and physiochemical properties of metal oxide and semiconductor nanoparticles; and for the studies of interactions of nanoparticles with their surrounding materials and among themselves. The role of multiscale modeling, involving both methods and applications, in nanoparticle research is discussed. The challenges and opportunities in the future are briefly discussed at the end. read less USED (low confidence) N. Marks, B. S. Thomas, K. L. Smith, and G. Lumpkin, “Thermal spike recrystallisation: Molecular dynamics simulation of radiation damage in polymorphs of titania,” Nuclear Instruments & Methods in Physics Research Section B-beam Interactions With Materials and Atoms. 2008. link Times cited: 23 USED (low confidence) V. V. Hoang, “The glass transition and thermodynamics of liquid and amorphous TiO2 nanoparticles,” Nanotechnology. 2008. link Times cited: 38 Abstract: The glass transition and thermodynamics of spherical liquid … read moreAbstract: The glass transition and thermodynamics of spherical liquid TiO2 nanoparticles, with different sizes ranging from 2 to 5 nm, have been studied in a model under non-periodic boundary conditions. We use the pairwise interatomic potentials proposed by Matsui and Akaogi. Models have been obtained by cooling from the melt via molecular dynamics (MD) simulation. The structural properties of liquid nanoparticles at 3500 K have been analyzed in detail through the partial radial distribution functions (PRDFs), coordination number distributions, bond-angle distributions and interatomic distances. Moreover, we also show the radial density profile in nanoparticles. Calculations show that size effects on the structure of a model are significant and that liquid TiO2 nanoparticles have a distorted pentahedral network structure with the mean coordination numbers ZTi–O≈5.0 and ZO–Ti≈2.5, while amorphous TiO2 nanoparticles have an octahedral network structure. The temperature dependence of the surface structure and surface energy of the nanoparticles has been obtained and is presented. In addition, the size dependence of the glass transition temperature and the temperature dependence of the diffusion constant of atomic species have been found and are discussed. read less USED (low confidence) P. Mitev and K. Hermansson, “Surface properties of rutile TiO2(1 1 0) from molecular dynamics and lattice dynamics at 300 K: Variable-charge model results,” Surface Science. 2007. link Times cited: 8 USED (low confidence) N. J. English, D. Sorescu, and J. Johnson, “Effects of an external electromagnetic field on rutile Tio2: A molecular dynamics study,” Journal of Physics and Chemistry of Solids. 2006. link Times cited: 25 USED (low confidence) K. Trachenko, M. Dove, E. Artacho, I. Todorov, and W. Smith, “Atomistic simulations of resistance to amorphization by radiation damage,” Physical Review B. 2006. link Times cited: 71 Abstract: We use molecular-dynamics simulations to study processes rel… read moreAbstract: We use molecular-dynamics simulations to study processes related to resistance to amorphization by radiation damage. We simulate high-energy radiation events in ${\mathrm{SiO}}_{2}$, ${\mathrm{GeO}}_{2}$, ${\mathrm{TiO}}_{2}$, ${\mathrm{Al}}_{2}{\mathrm{O}}_{3}$, and $\mathrm{MgO}$, and find that simulation results match the experiments. We discuss the difference between the damage that the structures along this series can support. We find that for the same material, activation barriers for damage recovery can strongly depend on the degree of structural damage. We observe that the effect of resistance to amorphization is primarily governed by the relaxation processes at the time scales of several picoseconds. On this time scale, we observe two distinct relaxation processes, reversible elastic deformation around the radiation cascade and recovery of the in-cascade damage of high topological disorder. Finally, we discuss how resistance to amorphization is related to interatomic interactions and to the nature of the chemical bond. read less USED (low confidence) B. S. Thomas, N. Marks, L. Corrales, and R. Devanathan, “Threshold displacement energies in rutile TiO2: A molecular dynamics simulation study,” Nuclear Instruments & Methods in Physics Research Section B-beam Interactions With Materials and Atoms. 2005. link Times cited: 53 USED (low confidence) B. S. Thomas, N. Marks, and B. D. Begg, “Empirical variable-charge models for titanium oxides: A study in transferability,” Physical Review B. 2004. link Times cited: 23 Abstract: The study of solid-state ionic systems hinges on the calcula… read moreAbstract: The study of solid-state ionic systems hinges on the calculation of electrostatic forces between charged ions. Recently, empirical models incorporating variable-charge schemes have been developed for titanium oxides and other ionic solids, combining the charge equilibration scheme with short-range Morse-stretch potentials (MS-Q models). This study considers the most recent MS-Q model for titanium oxides [V. Swamy and J. D. Gale. Phys. Rev. B 62, 5406 (2000)] and explores the contribution of the variable-charge scheme to the computed interatomic forces and crystalline properties. This work shows that the successes and failures of this and other published MS-Q models are due almost entirely to the Morse-stretch potential, with little to no contribution from electrostatic forces between the variable charges. This limits the transferability of such models and calls into question their functional form. Efforts to improve the MS-Q scheme by increasing the charge magnitudes and changing the description of the electrostatic forces do not improve the transferability. Such models require further development before they can compete in performance with well-established fixed-charge empirical models. read less USED (low confidence) D. Cooke, S. C. Parker, and D. Osguthorpe, “Calculating the vibrational thermodynamic properties of bulk oxides using lattice dynamics and molecular dynamics,” Physical Review B. 2003. link Times cited: 13 Abstract: In this paper we outline an approach for calculating the vib… read moreAbstract: In this paper we outline an approach for calculating the vibrational thermodynamic properties of an inorganic solid from a molecular dynamics simulation and then compare them with those evaluated, using the more established lattice dynamics approach. Our motivations are twofold. First, lattice dynamics is impractical for simulations of more than a few hundred atoms, whereas molecular dynamics can readily be applied to systems of several thousand atoms. Second, lattice dynamics incorporates a quasiharmonic approximation and is therefore unreliable when anharmonic effects dominate. The vibrational properties of three oxides, MgO, ${\mathrm{TiO}}_{2},$ and ${\mathrm{Fe}}_{2}{\mathrm{O}}_{3},$ were calculated over a range of temperatures between 300 K and 1500 K. The results show good agreement in their predicted phonon density of states and in the calculated vibrational contribution to the free energy over the entire temperature range considered. read less USED (low confidence) N. Dubrovinskaia, L. Dubrovinsky, V. Swamy, and R. Ahuja, “Cotunnite-Structured Titanium Dioxide,” High Pressure Research. 2002. link Times cited: 9 Abstract: Combined theoretical and experimental studies led to discove… read moreAbstract: Combined theoretical and experimental studies led to discovery of a new polymorph modification of titanium dioxide with nine-coordinated titanium. Among polycrystalline materials, it is one of the least compressible (with a bulk modulus of 431 GPa) and hardest (with a microhardness of 38 GPa). read less USED (low confidence) V. Swamy and L. Dubrovinsky, “Bulk modulus of anatase,” Journal of Physics and Chemistry of Solids. 2001. link Times cited: 39 USED (low confidence) V. Swamy, J. Gale, and L. Dubrovinsky, “Atomistic simulation of the crystal structures and bulk moduli of TiO,” Journal of Physics and Chemistry of Solids. 2001. link Times cited: 100 USED (low confidence) H. Nörenberg and J. Harding, “Ca-induced surface reconstructions on TiO2(110) studied by scanning tunneling microscopy, reflection high-energy electron diffraction and atomistic simulation,” Surface Science. 2001. link Times cited: 14 USED (low confidence) A. Howard, C. Mitchell, D. Morris, R. Egdell, and S. Parker, “The surface structure of TiO2(210) studied by atomically resolved STM and atomistic simulation,” Surface Science. 2000. link Times cited: 19 USED (low confidence) H. Nörenberg and J. Harding, “Formation of highly ordered Ca-overlayers on TiO2(110) surfaces studied by scanning tunneling microscopy and atomistic simulation,” Applied Surface Science. 1999. link Times cited: 9 USED (low confidence) M. S. S. Miguel, C. J. Calzado, and J. F. Sanz, “Molecular dynamics simulations of Na deposition on the TiO2(110) surface,” Surface Science. 1998. link Times cited: 28 USED (low confidence) D.-W. Kim, N. Enomoto, Z. Nakagawa, and K. Kawamura, “Molecular Dynamic Simulation in Titanium Dioxide Polymorphs: Rutile, Brookite, and Anatase,” Journal of the American Ceramic Society. 1996. link Times cited: 92 Abstract: Molecular dynamic (MD) simulations with a quantum correction… read moreAbstract: Molecular dynamic (MD) simulations with a quantum correction were performed on the titanium dioxide polymorphs. Interatomic potential functions of our new model are composed of Coulomb, short-range repulsion, van der Waals, and Morse interactions. The energy parameters were empirically determined to reproduce the fundamental properties of rutile crystal. The optimized crystal structure of TiO2, rutile, was in very good agreement with experimental data in the literature. For brookite and anatase, our MD simulations reproduced well the crystal structures and several physical properties, including volume thermal expansivity and bulk modulus. The present MD simulations with a new interatomic potential function and parameters successfully predicted the crystal structures of the titanium dioxide polymorphs. read less USED (low confidence) P. M. Oliver, S. C. Parker, J. Purton, and D. Bullett, “Atomistic simulations and electronic structure of TiO2(100) surfaces,” Surface Science. 1994. link Times cited: 16 USED (low confidence) F. Parrino, F. R. Pomilla, G. Camera-Roda, V. Loddo, and L. Palmisano, “Properties of titanium dioxide.” 2021. link Times cited: 5 USED (low confidence) R. Evarestov, “Simulations of Nanotube Properties.” 2020. link Times cited: 0 USED (low confidence) Y. Kusumawati, L. D. Astuti, E. Santoso, and S. Akhlus, “The comparison of nitroxide radical derivative compound interaction with brookite and anatase surface: A guide to choose the best photoanode for DSSC application.” 2020. link Times cited: 0 USED (low confidence) R. Evarestov, “Binary Oxides of Transition Metals: ZnO, TiO$_2, ZrO_2, HfO_2$.” 2020. link Times cited: 0 USED (low confidence) V. Baric, J. Laube, S. Salameh, L. Ciacchi, and L. Mädler, “A Contact Model for the Discrete Element Simulations of Aggregated Nanoparticle Films,” Particles in Contact. 2019. link Times cited: 3 USED (low confidence) E. Inclan, D. Geohegan, and M. Yoon, “A hybrid optimization algorithm to explore atomic configurations of TiO2 nanoparticles,” Computational Materials Science. 2018. link Times cited: 4 USED (low confidence) Y. Zhang, “Molecular Dynamics Study on Nanoparticle Collision and Coalescence.” 2017. link Times cited: 2 USED (low confidence) R. Maphanga and P. Ngoepe, “Computational Modelling as a Value Add in Energy Storage Materials.” 2016. link Times cited: 1 USED (low confidence) R. J. V. Valk, P. J. Dwyer, and S. Kelty, “Mitigation of Surface Aggregation in Modified Phthalocyanines as Potential Photo Sensitizers,” MRS Proceedings. 2015. link Times cited: 0 Abstract: Important to the development of dye-sensitized solar cells i… read moreAbstract: Important to the development of dye-sensitized solar cells is the longevity and photo-conversion efficiency of the dye. To improve cost effectiveness, dyes of superior thermal and chemical stability are desirable to extend device performance. In this study, we examine a series of peripherally fluorinated Zinc-Phthalocyanines (F x ZnPc). Introduction of chemically inert fluorine and isopropyl fluoroalkyl groups on the periphery of the Pc improve the dye stability and allow for tunable photo-physical properties. Additionally, introduction of the bulky isopropyl fluoroalkyl groups help mitigate molecular aggregation in thin films which is known to be detrimental to maintaining the desired photo-physical properties of the surface coating. Using molecular dynamics and first principles modeling, various substituent effects on surface adhesion and aggregation over TiO 2 surfaces are characterized for both symmetric and asymmetric substitution. read less USED (low confidence) R. Zhou, “Metal Oxides and Related Nanostructures.” 2015. link Times cited: 1 USED (low confidence) W. Yong, E. Dachs, A. Benisek, and R. Secco, “Heat capacity and entropy of rutile and TiO2II: Thermodynamic calculation of rutile–TiO2II transition boundary,” Physics of the Earth and Planetary Interiors. 2014. link Times cited: 12 USED (low confidence) A. Hallil, J. Raulot, and M. Cherkaoui, “Atomistic simulations of Cu2O bulk and Cu/Cu2O interface properties by using a new interatomic potential,” Computational Materials Science. 2014. link Times cited: 10 USED (low confidence) S. Walia et al., “Progress in Materials Science.” 2013. link Times cited: 0 USED (low confidence) M. Akindeju and P. Ong, “Controlling particle size in a novel spinning disc continuous stir tank and settler reactor for the continuous synthesis of titania,” Computer-aided chemical engineering. 2011. link Times cited: 1 USED (low confidence) Y. Shirakawa, A. Konishi, K. Kadota, S. Harada, A. Shimosaka, and J. Hidaka, “Effect of interfacial structures on ionic conductivity in particle-dispersed composite electrolytes,” Advanced Powder Technology. 2006. link Times cited: 3 Abstract: Enhancement of ionic conduction in NaCl-Al 2 O 3 and NaCl-Ti… read moreAbstract: Enhancement of ionic conduction in NaCl-Al 2 O 3 and NaCl-TiO 2 composites has been investigated by non-equilibrium molecular dynamics (NEMD) simulations. For quantitative discussion of ionic diffusion in NaCl matrices, activation energy of sodium vacancy V Na in an imperfect NaCl crystal was initially evaluated from results of NEMD simulations under some electric fields. The activation energy agrees well with experimental data. Simulations with NaCl(100)-Al 2 O 3 (110) and NaCl(100)-TiO 2 (001) hetero-interfaces have been performed for clarifying vacancy motion near interfaces. Structural disorder appeared around the hetero-interface. The simulation cells were constituted of ordered and disordered structure even if in equilibrium state without applying an electric field. The vacancies near the hetero-interface show large diffusion constants on the ionic conductivity in the present NEMD simulations. It seems that the vacancy motion near the interface contributes to the enhancement of the conduction in the composites. read less USED (low confidence) B. S. Thomas, N. Marks, and B. D. Begg, “Developing pair potentials for simulating radiation damage in complex oxides,” Nuclear Instruments & Methods in Physics Research Section B-beam Interactions With Materials and Atoms. 2005. link Times cited: 43 USED (low confidence) M. Miguel, C. Calzado, and J. Sanz, “First principles study of Na adsorption on TiO2 (110) surface,” International Journal of Quantum Chemistry. 1998. link Times cited: 14 Abstract: The activation of the (110) TiO2 rutile surface by depositio… read moreAbstract: The activation of the (110) TiO2 rutile surface by deposition of alkali metal atoms has been the subject of some recent experimental studies. These results indicate a reduction of the surface when sodium atoms are deposited on it. In the present work, this process has been studied by means of ab initio embedded cluster calculations combined with molecular dynamics simulations. Several surface sites have been considered and our calculations show that reduction occurs selectively on fivefold coordinated titanium atoms. Geometry optimization of a representative Na-surface clusters leads to a structure in which the Na atom is symmetrically coordinated to three oxygen atoms (two protruded and one basal) in excellent agreement with models proposed from experimental data. A mechanism for the adsorption process in which a long-distance electron transfer from atomic Na toward a fivefold coordinated surface titanium atom followed by physisorption of the Na+ cation on the surface is proposed. © 1998 John Wiley & Sons, Inc. Int J Quant Chem 70: 351–357, 1998 read less NOT USED (low confidence) N. Izzudin et al., “Simultaneous remediation of hexavalent chromium and organic pollutants in wastewater using period 4 transition metal oxide-based photocatalysts: a review,” Environmental Chemistry Letters. 2021. link Times cited: 20 NOT USED (low confidence) S. Jiao et al., “The lab-to-fab journey of copper-based electrocatalysts for multi-carbon production: Advances, challenges, and opportunities,” Nano Today. 2021. link Times cited: 17 NOT USED (low confidence) T. G. Rodríguez, J. Reyes-Nava, M. Pacio, H. Juárez, and J. Muñiz, “Theoretical study on the electronic structure properties of a PbS quantum dot adsorbed on TiO2 substrates and their role on solid-state devices,” Computational and Theoretical Chemistry. 2017. link Times cited: 0 NOT USED (low confidence) L. E. Oi, M.-Y. Choo, H. Lee, H. C. Ong, S. B. A. Hamid, and J. Juan, “Recent advances of titanium dioxide (TiO2) for green organic synthesis,” RSC Advances. 2016. link Times cited: 100 Abstract: Titanium dioxide (TiO2) has become increasingly popular as a… read moreAbstract: Titanium dioxide (TiO2) has become increasingly popular as a catalyst. Although many applications of TiO2 involve photocatalysis and photoelectrochemical reactions, there are numerous interesting discoveries of TiO2 for other reactions. This review focuses on the recent development of TiO2 as a catalyst in green organic synthesis including in hydrodeoxygenation, hydrogenation, esterification/transesterification, the water–gas shift reaction, and visible light-induced organic transformation owing to its strong metal-support interaction (SMSI), high chemical stability, acidity, and high redox reaction at low temperature. The relationship between the catalytic performance and different metal or metal oxide dopants, and different polymorphs of TiO2 are discussed in detail. It is interesting to note that the reduction temperature and addition of promoters have a significant effect on the catalytic performance of TiO2. read less NOT USED (low confidence) B. Luan, T. Huynh, and R. Zhou, “Simplified TiO2 force fields for studies of its interaction with biomolecules.,” The Journal of chemical physics. 2015. link Times cited: 41 Abstract: Engineered TiO2 nanoparticles have been routinely applied in… read moreAbstract: Engineered TiO2 nanoparticles have been routinely applied in nanotechnology, as well as in cosmetics and food industries. Despite active experimental studies intended to clarify TiO2's biological effects, including potential toxicity, the relation between experimentally inferred nanotoxicity and industry standards for safely applying nanoparticles remains somewhat ambiguous with justified concerns. Supplemental to experiments, molecular dynamics simulations have proven to be efficacious in investigating the molecular mechanism of a biological process occurring at nanoscale. In this article, to facilitate the nanotoxicity and nanomedicine research related to this important metal oxide, we provide a simplified force field, based on the original Matsui-Akaogi force field but compatible to the Lennard-Jones potentials normally used in modeling biomolecules, for simulating TiO2 nanoparticles interacting with biomolecules. The force field parameters were tested in simulating the bulk structure of TiO2, TiO2 nanoparticle-water interaction, as well as the adsorption of proteins on the TiO2 nanoparticle. We demonstrate that these simulation results are consistent with experimental data/observations. We expect that simulations will help to better understand the interaction between TiO2 and molecules. read less NOT USED (low confidence) D. Mathieu, “Formation Enthalpies Derived from Pairwise Interactions: A Step toward More Transferable Reactive Potentials for Organic Compounds.,” Journal of chemical theory and computation. 2012. link Times cited: 4 Abstract: A new approach to the development and parametrization of rea… read moreAbstract: A new approach to the development and parametrization of reactive potentials for organic compounds is put forward. As a byproduct of preliminary efforts in this direction, the performance of a simple representation of the energy of equilibrium structures in term of pairwise atom-atom and bond-bond contributions is investigated. For now, each contribution is assumed constant, given the multiplicity of covalent bonds, rather than computed on-the-fly from geometries and bond orders. In spite of this rough approximation, the approach performs remarkably well by comparison with semiempirical quantum chemical methods. Nevertheless, further refinement proves necessary for some unstable species involved in chemical reactions. As it stands, the present model appears as a promising basis in view of less empirical and more versatile alternatives to group contribution methods for the fast prediction of heats of formation, although much work remains to be done to demonstrate its value as a starting point toward better reactive potentials. read less NOT USED (high confidence) G. D. D. Liberto, Á. Morales‐García, and S. Bromley, “An unconstrained approach to systematic structural and energetic screening of materials interfaces,” Nature Communications. 2022. link Times cited: 4 NOT USED (high confidence) J. Medvedeva et al., “Structure and electronic properties of amorphous strontium titanate,” Physical Review Materials. 2022. link Times cited: 0 Abstract: Understanding the short-range structure of an amorphous mate… read moreAbstract: Understanding the short-range structure of an amorphous material is the first step in predicting its macroscopic properties. Amorphous strontium titanate (a-STO) presents a unique challenge due to contradictory experimental findings regarding the local oxygen environment of titanium, concluded to be either tetrahedral or octahedral. To elucidate the discrepancy, 72 models of a-STO with density ranging from the crystalline value 5.12 to 3 . 07 g / cm 3 were prepared using abinitio molecular dynamics liquid-quench simulations and characterized by extended x-ray absorption fine structure (EXAFS) for both Ti and Sr K edge. An excellent agreement between the calculated and two independent experimental EXAFS measurements demonstrates that the discrepancy in the Ti coordination stems from differences in the material’s density. Next, density-dependent structural characteristics, including Ti-O and Sr-O coordination, distances, angles, polyhedral sharing, and vibrational density of states in a-STO are thoroughly analyzed and correlated with disorder-induced changes in the electronic properties that are calculated using a hybrid density functional. The obtained increase in the band gap and broadening of Ti- d e g -orbital contributions in the conduction band are in excellent agreement with our x-ray absorption spectroscopy for Ti L-edge spectra and optical absorption measurements for crystalline and amorphous STO grown by pulsed laser deposition. The derived microscopic understanding of the structure-property relationship in amorphous “perovskite” serves as a foundation for further investigations of a-STO and related materials. read less NOT USED (high confidence) P. Siani, G. Frigerio, E. Donadoni, and C. D. Valentin, “Molecular dynamics simulations of cRGD-conjugated PEGylated TiO2 nanoparticles for targeted photodynamic therapy.,” Journal of colloid and interface science. 2022. link Times cited: 6 NOT USED (high confidence) B. Samanta et al., “Challenges of modeling nanostructured materials for photocatalytic water splitting.,” Chemical Society reviews. 2022. link Times cited: 22 Abstract: Understanding the water splitting mechanism in photocatalysi… read moreAbstract: Understanding the water splitting mechanism in photocatalysis is a rewarding goal as it will allow producing clean fuel for a sustainable life in the future. However, identifying the photocatalytic mechanisms by modeling photoactive nanoparticles requires sophisticated computational techniques based on multiscale modeling. In this review, we will survey the strengths and drawbacks of currently available theoretical methods at different length and accuracy scales. Understanding the surface-active site through Density Functional Theory (DFT) using new, more accurate exchange-correlation functionals plays a key role for surface engineering. Larger scale dynamics of the catalyst/electrolyte interface can be treated with Molecular Dynamics albeit there is a need for more generalizations of force fields. Monte Carlo and Continuum Modeling techniques are so far not the prominent path for modeling water splitting but interest is growing due to the lower computational cost and the feasibility to compare the modeling outcome directly to experimental data. The future challenges in modeling complex nano-photocatalysts involve combining different methods in a hierarchical way so that resources are spent wisely at each length scale, as well as accounting for excited states chemistry that is important for photocatalysis, a path that will bring devices closer to the theoretical limit of photocatalytic efficiency. read less NOT USED (high confidence) A. Kupferer, S. Mändl, and S. G. Mayr, “Tailoring morphology in titania nanotube arrays by implantation: experiments and modelling on designed pore size—and beyond,” Materials Research Letters. 2021. link Times cited: 3 Abstract: Titania nanotube arrays are an exceptionally adaptable mater… read moreAbstract: Titania nanotube arrays are an exceptionally adaptable material for various applications ranging from energy conversion to biomedicine. Besides electronic properties, structural morphology on nanometre scale is essential. It is demonstrated that ion implantation constitutes a versatile method for the synthesis of tailored nanotube morphologies. Experimental-phenomenological observations reveal a successive closing behaviour of nanotubes upon ion implantation. Employing molecular dynamics calculations in combination with analytical continuum models, the physical origins of this scenario are unravelled by identifying ion bombardment induced viscous flow driven by capillarity as its underlying mechanism besides minor contributions from sputtering and redeposition. These findings enable the tailoring of nanotube arrays suitable for manifold applications. GRAPHICAL ABSTRACT IMPACT STATEMENT This work presents a unified framework for understanding and predicting ion-induced effects in nanotube structures by a combination of experiments, modelling and analytical theory. read less NOT USED (high confidence) M. Roodbari, M. Abbasi, S. Arabha, A. Gharedaghi, and A. Rajabpour, “11Interfacial thermal conductance between TiO2 nanoparticle and water: A molecular dynamics study,” Journal of Molecular Liquids. 2021. link Times cited: 10 NOT USED (high confidence) I. Rouse et al., “First principles characterisation of bio-nano interface.,” Physical chemistry chemical physics : PCCP. 2021. link Times cited: 13 Abstract: Nanomaterials possess a wide range of potential applications… read moreAbstract: Nanomaterials possess a wide range of potential applications due to their novel properties and exceptionally high activity as a result of their large surface to volume ratios compared to bulk matter. The active surface may present both advantage and risk when the nanomaterials interact with living organisms. As the overall biological impact of nanomaterials is triggered and mediated by interactions at the bio-nano interface, an ability to predict those from the atomistic descriptors, especially before the material is produced, can present enormous advantage for the development of nanotechnology. Fast screening of nanomaterials and their variations for specific biological effects can be enabled using computational materials modelling. The challenge lies in the range of scales that needs to be crossed from the material-specific atomistic representation to the relevant length scales covering typical biomolecules (proteins and lipids). In this work, we present a systematic multiscale approach that allows one to evaluate crucial interactions at the bionano interface from the first principles without any prior information about the material and thus establish links between the details of the nanomaterials structure to protein-nanoparticle interactions. As an example, an advanced computational characterization of titanium dioxide nanoparticles (6 different surfaces of rutile and anatase polymorphs) has been performed. We computed characteristics of the titanium dioxide interface with water using density functional theory for electronic density, used these parameters to derive an atomistic force field, and calculated adsorption energies for essential biomolecules on the surface of titania nanoparticles via direct atomistic simulations and coarse-grained molecular dynamics. Hydration energies, as well as adsorption energies for a set of 40 blood proteins are reported. read less NOT USED (high confidence) F. Meierhofer and U. Fritsching, “Synthesis of Metal Oxide Nanoparticles in Flame Sprays: Review on Process Technology, Modeling, and Diagnostics,” Energy & Fuels. 2021. link Times cited: 57 Abstract: The gas synthesis of nanoparticles has gained major interest… read moreAbstract: The gas synthesis of nanoparticles has gained major interest by different industries and research groups for the development of new materials and their subsequent implementation in numerous devices... read less NOT USED (high confidence) N. Politova-Brinkova, S. Tsibranska-Gyoreva, S. Tcholakova, N. Denkov, and T. Danner, “Preparation of TiO2 Nanoparticle Aggregates and Capsules by the ‘Two-Emulsion Method.’” 2020. link Times cited: 1 Abstract: TiO2-based materials are of great practical interest in seve… read moreAbstract: TiO2-based materials are of great practical interest in several technological areas. Both the size and the morphology of the TiO2 particles are of critical importance for their applications. The current study explores the effect of several factors on the outcome of the TiO2 particle synthesis via the so-called ‘two-emulsion method’. In this technique, two water-in-oil emulsions—each of them containing different reactant in the dispersed water drops—are mixed under well controlled conditions. Upon such mixing, partial coalescence of the water drops from the two emulsions leads to mixing of the drop content, with chemical reaction occurring within the drops, and to synthesis of Ti(OH)4 particles. Afterwards, the latter are transformed by emulsion heating into TiO2 particles and aggregates of predominantly anatase structure. Our results show that—depending on the precursor and surfactant concentrations, oil viscosity, emulsification time, and mixing speed—the obtained nanoparticles could aggregate either on the drop surface, forming capsules with a very smooth surface, or inside the water droplets, thus leading to hierarchically structured aggregates of micrometer size. The spherical smooth capsules are constructed of very small monodisperse TiO2 nanoparticles with size below 5 nm. The hierarchical bulk aggregates, on the other hand, are formed from bigger primary particles of sub-micrometer size. The obtained results show that one can obtain various TiO2 structures by controlling the conditions during the emulsion preparation and mixing read less NOT USED (high confidence) D. Mora‐Fonz, M. Kaviani, and A. Shluger, “Disorder-induced electron and hole trapping in amorphous
TiO2,” Physical Review B. 2020. link Times cited: 5 Abstract: Thin films of amorphous (a)-TiO2 are ubiquitous as photocata… read moreAbstract: Thin films of amorphous (a)-TiO2 are ubiquitous as photocatalysts, protective coatings, photoanodes and in memory application, where they are exposed to excess electrons and holes. We investigate trapping of excess electrons and holes in the bulk of pure amorphous titanium dioxide, a-TiO2, using hybrid density functional theory (h-DFT) calculations. Fifty 270-atom a-TiO2 structures were produced using classical molecular dynamics and their geometries fully optimised using h-DFT simulations. They have the density, distribution of atomic coordination numbers and radial pair-distribution functions in agreement with experiment. The calculated average a-TiO2 band gap is 3.25 eV with no states splitting into the band gap. Trapping of excess electrons and holes in a-TiO2 is predicted at precursor sites, such as elongated Ti-O bonds. Single electron and hole polarons have average trapping energies (ET) of -0.4 eV and -0.8 eV, respectively. We also identify several types of electron and hole bipolaron states and discuss their stability. These results can be used for understanding the mechanisms of photo-catalysis and improving the performance of electronic devices employing a-TiO2 films. read less NOT USED (high confidence) M. M. Blazhynska et al., “Recent advances in theoretical investigation of titanium dioxide nanomaterials. A review.” 2020. link Times cited: 4 Abstract: Titanium dioxide (TiO2) is one of the most widely used nanom… read moreAbstract: Titanium dioxide (TiO2) is one of the most widely used nanomaterials in many emerging areas of material science, including solar energy harvesting and biomedical implanting. In this review, we present progress and recent achievements in the theory and computer simulations of the physicochemical properties of small TiO2 clusters, middle-size nanoparticles, as well as the liquid-solid interface. The historical overview and the development of empirical force fields for classical molecular dynamics (MD) of various TiO2 polymorphs, such as rutile, anatase, and brookite, are given. The adsorption behavior of solvent molecules, ions, small organic ligands, and biomacromolecules on TiO2 interfaces are examined with the aim of the understanding of driving forces and mechanisms, which govern binding and recognition between adsorbate and surfaces. The effects of crystal forms, crystallographic planes, surface defects, and solvent environments on the adsorption process are discussed. Structural details and dynamics of adsorption phenomena, occurring at liquid-solid interfaces, are overviewed starting from early empirical potential models up to recent reactive ReaxFF MD simulations, capable of capturing dissociative adsorption of water molecules. The performance of different theoretical methods, ranged from quantum mechanical (QM) calculations (ab initio and the density functional theory) up to classical force field and hybrid MM/QM simulations, is critically analyzed. In addition, the recent progress in computational chemistry of light-induced electronic processes, underlying the structure, dynamics, and functioning of molecular and hybrid materials is discussed with the focus on the solar energy applications in dye-sensitized solar cells (DSSC), which are currently under development. Besides, dye design principles, the role of anchoring moiety and dye aggregation in the DSSC performance are crucially analyzed. Finally, we outline the perspectives and challenges for further progress in research and promising directions in the development of accurate computational tools for modeling interactions between inorganic materials with not perfect structures and natural biomacromolecules at physiological conditions. read less NOT USED (high confidence) V. Esposito and I. Castelli, “Metastability at Defective Metal Oxide Interfaces and Nanoconfined Structures,” Advanced Materials Interfaces. 2020. link Times cited: 18 Abstract: Most of the paradigms in materials science and technology fi… read moreAbstract: Most of the paradigms in materials science and technology firmly rely on equilibrium materials, i.e., phases with the lowest Gibbs energy under thermodynamic conditions. In nature, however, complexity rules, and the other aspect is metastability. This review aims to provide a coherent description of such effects and to formulate hypotheses on the fundamental energetic mechanisms of residual metastability in crystalline metal oxide polymorphs. The authors especially focus on different forms of broken symmetry at the interface, e.g., induced by defects, lattice strain/stress, and elemental diffusion. The discussion also provides perspective on the technological implications and possibilities arising from identifying a general methodology for establishing metastability in polymorphic functional metal oxides for energy applications, catalysis, and electronics. read less NOT USED (high confidence) H. Alizadeh, M. Mostaan, N. Malih, and J. Davoodi, “Size and shape dependent thermal properties of rutile TiO2 nanoparticles: a molecular dynamics simulation study,” Molecular Simulation. 2020. link Times cited: 7 Abstract: ABSTRACT Molecular dynamics (MD) simulations, based on a rec… read moreAbstract: ABSTRACT Molecular dynamics (MD) simulations, based on a recently developed charge optimised many-body interatomic potential (COMB3) for titanium dioxide materials, have been employed to investigate the effects of size and shape on the thermal properties of rutile TiO2 nanoparticles (2–6 nm). The size and shape dependence of the melting temperature, cohesive energy, heat capacity and thermal expansion coefficients have been studied. Our MD simulation results show that the melting point of spherical nanoparticles increases with size increase. On the other hand, the heat capacity and thermal expansion coefficients decrease with increasing nanoparticle size. Also, to predict the thermal properties of rutile TiO2 nanoparticles, we merged two theoretical models (Qi-model and Zhu’s model) proposed for size and shape-dependent thermal properties of nanoparticles. The comparison between our MD simulation results with those predicted by theoretical models showed that the trends observed in our MD simulation results were in good agreement with those suggested by the theoretical models. However, the thermal properties obtained from MD simulations deviated from those calculated theoretically for small nanoparticles which could be due to the edge and corner effects disregarded in the theoretical model. read less NOT USED (high confidence) M. Stiller et al., “Titanium
3d
ferromagnetism with perpendicular anisotropy in defective anatase,” Physical Review B. 2020. link Times cited: 8 Abstract: Author(s): Stiller, M; N'Diaye, AT; Ohldag, H; Barzola-… read moreAbstract: Author(s): Stiller, M; N'Diaye, AT; Ohldag, H; Barzola-Quiquia, J; Esquinazi, PD; Amelal, T; Bundesmann, C; Spemann, D; Trautmann, M; Chasse, A; Hamed, HB; Adeagbo, WA; Hergert, W | Abstract: © 2020 American Physical Society. This work focuses on the generation of ferromagnetism at the surface of anatase TiO2 films by low-energy ion irradiation. Controlled Ar+-ion irradiation resulted in a thin (∼10) nm ferromagnetic surface layer. The intrinsic origin and robustness of the magnetic order has been characterized by x-ray magnetic circular dichroism at room temperature revealing that a Ti band is spin-polarized. These results, together with density functional theory calculations, indicate that Ti vacancy-interstitial pairs are responsible for the magnetic order. Superconducting quantum interference device measurements show the existence of a perpendicular magnetic anisotropy and a low remanent magnetization. Magnetic force microscopy reveals that this low remanence is due to oppositely aligned magnetic domains with magnetization vectors normal to the main surface. The weak domain-wall pinning, the magnetic anisotropy, together with the simplicity of the preparation method, open up interesting possibilities for future applications. As an example, single domain patterns of ∼1μm width and several μm length can be easily prepared. read less NOT USED (high confidence) K. Yang, L. Yang, C. Ai, Z. Wang, and S. Lin, “Elastic properties of anatase titanium dioxide nanotubes: A molecular dynamics study,” Chinese Physics B. 2019. link Times cited: 5 NOT USED (high confidence) A. Reinhardt, “Phase behavior of empirical potentials of titanium dioxide,” The Journal of Chemical Physics. 2019. link Times cited: 7 Abstract: In recent years, several relatively similar empirical models… read moreAbstract: In recent years, several relatively similar empirical models of titanium dioxide have been proposed as reparameterizations of the potential of Matsui and Akaogi, with the Buckingham interaction replaced by a Lennard-Jones interaction. However, because of the steepness of the repulsive region of the Lennard-Jones potential, such reparameterized models result in rather different mechanical and thermodynamic properties compared to the original potential. Here, we use free-energy calculations based on the Einstein crystal method to compute the phase diagram of both the Matsui–Akaogi potential and one of its Lennard-Jones-based reparameterizations. Both potentials are able to support a large number of distinct crystalline polymorphs of titanium dioxide that have been observed in experiment, but the regions of thermodynamic stability of the individual phases are significantly different from one another. Moreover, neither potential results in phase behavior that is fully consistent with the available experimental evidence.In recent years, several relatively similar empirical models of titanium dioxide have been proposed as reparameterizations of the potential of Matsui and Akaogi, with the Buckingham interaction replaced by a Lennard-Jones interaction. However, because of the steepness of the repulsive region of the Lennard-Jones potential, such reparameterized models result in rather different mechanical and thermodynamic properties compared to the original potential. Here, we use free-energy calculations based on the Einstein crystal method to compute the phase diagram of both the Matsui–Akaogi potential and one of its Lennard-Jones-based reparameterizations. Both potentials are able to support a large number of distinct crystalline polymorphs of titanium dioxide that have been observed in experiment, but the regions of thermodynamic stability of the individual phases are significantly different from one another. Moreover, neither potential results in phase behavior that is fully consistent with the available experimenta... read less NOT USED (high confidence) Z. Xu, L. Zhang, L. Wang, J. Zuo, and M. Yang, “Computational characterization of the structural and mechanical properties of nanoporous titania,” RSC Advances. 2019. link Times cited: 4 Abstract: Nanoporous titania is one of the most commonly used biomater… read moreAbstract: Nanoporous titania is one of the most commonly used biomaterials with good biocompatibility and mechanical strength. Understanding to the influence of pore structures on their performances is crucial for the design and preparation of titania-based materials. Two kinds of structural models for nanoporous titania were constructed and used to investigate the effect of pore size and/or porosity on their mechanical properties by using molecular dynamic simulations with the Matsui–Akaogi potentials. The porous structures were relaxed and their elastic constants were computed and used to evaluated their bulk, shear and Young's moduli. Overlap effect in small pores, pore size and porosity have considerable influence on computed elastic moduli. Compared to bulk rutile TiO2, reduced mechanical moduli were predicted. Simulations on uniaxial tensile tests revealed an anisotropic stress–strain relationship and a brittle-to-ductile transition for structures with large porosities. Fracture failure was predicted for all the studied porous structures. The maximum stress decreases with pore size and porosity, while the corresponding strain decreases with pore size, but increases with porosity. read less NOT USED (high confidence) Á. Morales‐García, A. M. Escatllar, F. Illas, and S. Bromley, “Understanding the interplay between size, morphology and energy gap in photoactive TiO2 nanoparticles.,” Nanoscale. 2019. link Times cited: 28 Abstract: Anatase TiO2 nanoparticles (NPs) have the potential to photo… read moreAbstract: Anatase TiO2 nanoparticles (NPs) have the potential to photocatalyse water splitting using UV light, to thus provide hydrogen fuel in a clean and sustainable manner. Such NPs have optical gaps covering a small range of relatively high energy solar photons, giving rise to low photo-efficiencies. Although anatase NPs with 10-20 nm diameters thermodynamically prefer crystalline faceted morphologies, application of physico-chemical procedures can produce more rounded NPs with amorphous shells. Such engineered metastable core-shell NPs (so-called black TiO2 NPs) have reduced band gaps due to shell-induced band edge broadening, resulting in higher photoactivities. For <5 nm diameters, TiO2 NPs typically exhibit spherical-like NP morphologies, which also display enhanced photoactivity. For smaller NPs it is difficult to experimentally determine their thermodynamic stability and internal atomic structure, to help rationalise their higher photoactivities. Employing accurate electronic structure calculations, we establish the relative stability of spherical and faceted stoichiometric TiO2 NPs with 1-3.4 nm diameters. Mirroring experimental preparation, simulated thermal annealing is found to significantly stabilise relaxed spherical cut anatase NPs. We find that the smallest spherical NPs become amorphized by annealing, but, for diameters >2 nm, annealing yields NPs with anatase-cores and amorphous-shells. Like larger black TiO2 core-shell NPs, we confirm that our core-shell NPs are metastable relative to faceted anatase NPs and have significantly smaller optical gaps than faceted NPs. Our calculated gaps are in excellent agreement with experimental data, strongly supporting the validity of our NP models. Energy gap narrowing in these core-shell NPs is found to be due to broadening of valence band states induced by the amorphous shell, analogous to the mechanism proposed for black TiO2 NPs. Our stoichiometric NPs also show that this band narrowing effect does not require the disordered shells to be non-stoichiometric or for incorporation of other atom types. Instead, we find that this effect mainly arises from 4-coordinated Ti atoms in the amorphous shell. Our careful and systematic computational investigation, using NP models of unprecedented realism, thus provides direct confirmation that the enhanced photoactivity in small spherical TiO2 NP observed in experiment is due to the formation of metastable core-shell NPs with 4-coordinated Ti centres. read less NOT USED (high confidence) A. Barmeh, M. Nilforoushan, and S. Otroj, “Photocatalytic and self-cleaning properties of glazed ceramic tiles coated with TiO2 and Al-doped TiO2 thin films,” Journal of the Australian Ceramic Society. 2019. link Times cited: 2 NOT USED (high confidence) T. D. Ta, A. K. Tieu, H. Zhu, S. Wan, H. Phan, and J. Hao, “Influence of molecular structure on lubrication of aqueous triblock copolymer lubricants between rutile surfaces: An MD approach,” Tribology International. 2019. link Times cited: 8 NOT USED (high confidence) L. Yang et al., “Thermal conductivity of TiO2 nanotube: a molecular dynamics study,” Journal of Physics: Condensed Matter. 2018. link Times cited: 3 Abstract: The thermal conductivity of anatase TiO2 nanotubes was inves… read moreAbstract: The thermal conductivity of anatase TiO2 nanotubes was investigated using equilibrium molecular dynamics simulations based on Green-Kubo formalism. The calculated thermal conductivity of for anatase crystal at room temperature agrees well with experimental value of ~8.5 W K−1 · m−1, demonstrating that the method used in our calculation can provide a good description for the thermal transport of TiO2. The dependence of the thermal conductivity of TiO2 nanotubes with temperature, tube size and chirality were studied in detail. The relationship between the thermal conductivity and the vibrational density-of-states of the nanotubes was also investigated. read less NOT USED (high confidence) M. Mostaan, J. Davoodi, H. Alizadeh, and M. Yarifard, “Nontrivial tensile behavior of rutile TiO2 nanowires: a molecular dynamics study,” The European Physical Journal B. 2018. link Times cited: 2 NOT USED (high confidence) K. Yang et al., “New insights into the atomic structure of amorphous TiO2 using tight-binding molecular dynamics.,” The Journal of chemical physics. 2018. link Times cited: 12 Abstract: Amorphous TiO2 (a-TiO2) could offer an attractive alternativ… read moreAbstract: Amorphous TiO2 (a-TiO2) could offer an attractive alternative to conventional crystalline TiO2 phases for photocatalytic applications. However, the atomic structure of a-TiO2 remains poorly understood with respect to that of its crystalline counterparts. Here, we conduct some classical molecular dynamics simulations of a-TiO2 based on a selection of empirical potentials. We show that, on account of its ability to dynamically assign the charge of each atom based on its local environment, the second-moment tight-binding charge equilibration potential yields an unprecedented agreement with available experimental data. Based on these simulations, we investigate the degree of order and disorder in a-TiO2. Overall, the results suggest that a-TiO2 features a large flexibility in its local topology, which may explain the high sensitivity of its structure to the synthesis method being used. read less NOT USED (high confidence) C. Lee, C.-F. Wu, and J. Jean, “Effects of CuO on constrained sintering of a polycrystalline TiO2
ceramics,” Journal of the American Ceramic Society. 2018. link Times cited: 7 NOT USED (high confidence) N. Kaliannan and K. Krishnamurthy, “Computational study on the structural and surface properties of amorphous hydroxylated TiO2 spherical nanoparticles,” Journal of Nanoparticle Research. 2017. link Times cited: 3 NOT USED (high confidence) F. Bai, W. Li, and H.-X. Zhang, “Theoretical Studies of Titanium Dioxide for Dye-Sensitized Solar Cell and Photocatalytic Reaction.” 2017. link Times cited: 7 Abstract: This chapter aims to provide researchers in the field of pho… read moreAbstract: This chapter aims to provide researchers in the field of photovoltaics with the valuable information and knowledge needed to understand the physics and modeling of titanium dioxide for dye-sensitized solar cell and photocatalytic reaction. The electronic band structure of titanium dioxide, the treatment of the excited state of titanium dioxide, the molecular dynamics and ultrafast quantum dynamics simulations, and several promis- ing photocatalytic schemes and important considerations for theoretical study are addressed and reviewed. The advanced computational strategies and methods and opti- mized models to achieve exact simulation are described and discussed, including first principle calculations, nonadiabatic molecular and quantum dynamics, wave function propagation methods, and surface construction of titanium dioxide. These advanced theoretical investigations have become highly active areas of photovoltaics research and powerful tools for the supplement and prediction of related experimental efforts. read less NOT USED (high confidence) N. Deskins, J. Du, and P. Rao, “The structural and electronic properties of reduced amorphous titania.,” Physical chemistry chemical physics : PCCP. 2017. link Times cited: 19 Abstract: Crystalline titania has been extensively studied using exper… read moreAbstract: Crystalline titania has been extensively studied using experimental and theoretical tools. Amorphous titania, however, has received less attention in the literature, despite its importance for a number of applications, such as photocatalysis, batteries, and electronic devices. In this work we modeled amorphous titania using a combination of molecular dynamics and density functional theory with several stoichiometries (TiOx, 2 ≥ x ≥ 1.75). Our results show that oxygen atom removal from amorphous titania is much easier than from crystalline titania, indicating that reduced amorphous structures are likely common. Ti atoms in amorphous titania exhibit a distribution of coordination numbers (five to seven), but the average coordination number of oxygen increases upon reduction. We also identified that gap states arise in substoichiometric titania due to the formation of Ti3+ centers. Such gap states are highly localized and randomly distributed across different Ti atoms, although we do observe a slight preference for electron localization on seven-coordinated Ti atoms. We observe that band gaps increase with reduction of amorphous titania. We also analyzed a proposed hole hopping mechanism involving oxygen vacancies by calculating hole hopping distances. We found that such distances are large except in very reduced states, indicating likely slow hole diffusion through an oxygen vacancy mechanism. Our work is the first of its kind to thoroughly characterize the structural and electronic properties of amorphous titania in reduced states. read less NOT USED (high confidence) G. Okeke, S. Antony, R. Hammond, and K. Ahmed, “Structures and orientation-dependent interaction forces of titania nanowires using molecular dynamics simulations,” Journal of Nanoparticle Research. 2017. link Times cited: 3 NOT USED (high confidence) Z. Khalifa, “Grain size reduction on nanostructured TiO2 thin films due to annealing,” RSC Advances. 2017. link Times cited: 19 Abstract: TiO2 thin films have been deposited at 300 °C on quartz subs… read moreAbstract: TiO2 thin films have been deposited at 300 °C on quartz substrates by a metal–organic chemical vapor deposition technique. The obtained films have been annealed at different temperatures up to 1100 °C. X-ray diffraction studies show that the obtained films maintain the anatase phase till 800 °C annealing temperature, and the rutile phase appears at 900 °C. Extra unidentified peaks appear at 1000 °C, and 1100 °C. Raman microscopy has been used to identify the obtained films. The obtained spectra show the normal modes of vibrations of the pure and mixed phases. Scanning electron microscopy graphs show grain size shrinkage concurrent to the appearance of the rutile phase. A slight band gap reduction has been calculated from UV-Vis transmittance spectrophotometery measurements. DC conductivity curves show three regions with different activation energies. read less NOT USED (high confidence) M. Matas and J. Houška, “Strong effect of the interaction potential cut-off on the crystallinity of films grown by simulations,” Molecular Simulation. 2017. link Times cited: 0 Abstract: The paper deals with the methodology of film growth simulati… read moreAbstract: The paper deals with the methodology of film growth simulations using classical molecular dynamics and an empirical interaction potential. We focus on the effect of the cut-off distance (rC) of the short-range part of the potential. On the one hand, we find that rC does not affect the qualitative conclusions of the simulations and that its quantitative effect is in the logical direction (better crystallinity at higher rC). On the other hand, we show that the aforementioned quantitative effect is very strong, and clearly underestimated in the literature. The film crystallinity is affected by (non-)neglecting of as seemingly low energies as several meV per bond. The results are important for the design of growth simulations of crystalline films and for the correct interpretation of their results. read less NOT USED (high confidence) A. Bandura, S. I. Lukyanov, and R. Evarestov, “Atom–atom force field for simulation of zirconia bulk, nanosheets and nanotubes,” Molecular Simulation. 2017. link Times cited: 7 Abstract: The set of three pair atom–atom potentials for zirconia crys… read moreAbstract: The set of three pair atom–atom potentials for zirconia crystals and nano objects was developed. Besides Buckingham potential and Coulomb interaction, these force fields employ the additional functional forms: Fermi-Dirac, Inverse Gaussian or Morse potential. The developed force fields are capable to reproduce the structural, mechanical and thermodynamic properties of five zirconia phases: monoclinic, tetragonal, cubic, brookite and cotunnite with acceptable accuracy. The proposed force fields give monoclinic phase as a ground state structure and predict the correct energy ordering of the phases. The Raman and IR phonon frequencies, temperature dependencies of the thermodynamic properties of monoclinic and tetragonal zirconia are predicted in good and moderate agreement with the experimentally observed data and results of first-principles calculations. To test the transferability of proposed potentials, the zirconia-based nanosheets and nanotubes were simulated. Results of structure optimisation and calculation of the nanotubes’ strain energies are well compared with the corresponding data of the first-principles calculations. read less NOT USED (high confidence) A. Mattoni, A. Filippetti, and C. Caddeo, “Modeling hybrid perovskites by molecular dynamics,” Journal of Physics: Condensed Matter. 2017. link Times cited: 70 Abstract: The topical review describes the recent progress in the mode… read moreAbstract: The topical review describes the recent progress in the modeling of hybrid perovskites by molecular dynamics simulations. Hybrid perovskites and in particular methylammonium lead halide (MAPI) have a tremendous technological relevance representing the fastest-advancing solar material to date. They also represent the paradigm of an organic–inorganic crystalline material with some conceptual peculiarities: an inorganic semiconductor for what concerns the electronic and absorption properties with a hybrid and solution processable organic–inorganic body. After briefly explaining the basic concepts of ab initio and classical molecular dynamics, the model potential recently developed for hybrid perovskites is described together with its physical motivation as a simple ionic model able to reproduce the main dynamical properties of the material. Advantages and limits of the two strategies (either ab initio or classical) are discussed in comparison with the time and length scales (from pico to microsecond scale) necessary to comprehensively study the relevant properties of hybrid perovskites from molecular reorientations to electrocaloric effects. The state-of-the-art of the molecular dynamics modeling of hybrid perovskites is reviewed by focusing on a selection of showcase applications of methylammonium lead halide: molecular cations disorder; temperature evolution of vibrations; thermally activated defects diffusion; thermal transport. We finally discuss the perspectives in the modeling of hybrid perovskites by molecular dynamics. read less NOT USED (high confidence) C. Wei, L. Linghong, H. Liangliang, D. Yihui, and L. Xiaohua, “Molecular Behavior of Water on Titanium Dioxide Nanotubes: A Molecular Dynamics Simulation Study,” Journal of Chemical & Engineering Data. 2016. link Times cited: 12 Abstract: Understanding molecular behavior of water on titanium dioxid… read moreAbstract: Understanding molecular behavior of water on titanium dioxide nanotubes (TiNTs) is of great interest in order to enable potential application of TiNTs in dye-sensitized solar cells, photocatalysis, and biomedical coatings. Using molecular dynamics simulations, we study the static and dynamic properties of water on TiNT with a diameter of ∼1.0 nm. The TiNT modified by a carbon nanotube (CNT) inside is built to investigate the effect of surface chemistry changes on the sorption and diffusion of water. The results show that the water molecules outside TiNT conform with the two-layer model for water on a planar surface. The difference is that the first water layer is further from Ti5c as an effect of surface curvature, indicating the easier water desorption on the surface. This layer disappears for water inside TiNT, leaving a water layer with the hydrogen atoms pointing to the O2c to form hydrogen bonds. The simulations also reveal that the orderly structure is destroyed in the carbon modified nanotubes. Dif... read less NOT USED (high confidence) Y. Zhu, Y. Zhang, Y. Shi, X. Lu, J. Li, and L. Lu, “Lubrication Behavior of Water Molecules Confined in TiO2 Nanoslits: A Molecular Dynamics Study,” Journal of Chemical & Engineering Data. 2016. link Times cited: 14 Abstract: Titanium (Ti) metal has been widely used in orthopedic impla… read moreAbstract: Titanium (Ti) metal has been widely used in orthopedic implants, such as knee replacements and fracture fixation devices, where water is the base fluid of the lubricant. In this work, a series of nonequilibrium molecular dynamics have been carried out to investigate the microstructure and lubrication of water molecules confined in TiO2 nanoslits under shearing. The effects of varying slit gap widths (0.8, 1.2, 1.6, and 2.0 nm) and shear velocities (200, 100, 50, and 10 m/s) on the friction coefficients between TiO2 and water molecules were evaluated to shed light on the role of the confined water molecules on lubrication. Simulation results showed that the friction coefficient decreased as the slit width increased. Detailed analysis of water molecules microstructure revealed that water molecules confined in the slits were layered. Typically, all the water molecules in Layer 1 and some water molecules in Layer 2 could reach the sliding velocity of the wall, which were in agreement with the reported mobilit... read less NOT USED (high confidence) J. Liu, X. Fan, C. Sun, and W. Zhu, “Oxidation of the titanium(0001) surface: diffusion processes of oxygen from DFT,” RSC Advances. 2016. link Times cited: 19 Abstract: The initial oxidation process of the Ti(0001) surface is inv… read moreAbstract: The initial oxidation process of the Ti(0001) surface is investigated based on the diffusion of oxygen with a potential barrier by first-principles methods. The results show that oxygen molecules can dissociate freely at the Ti surface without an energy barrier and oxygen atoms are chemisorbed on the face-centered cubic (FCC) site of the surface. At low oxygen coverage on the surface, the nearest-neighbor oxygen can assist the diffusion of oxygen from the surface into the sublayer, due to the decrease in the energy barrier. Based on the analysis of the adsorption energy and diffusion barrier, the double-layer model of oxygen adsorption is proposed. With this model, the change in work function is analyzed by following the increase in adsorbed oxygen from 0 to 200%, and is consistent with the experimental results. read less NOT USED (high confidence) M. Matshaba, D. Sayle, T. Sayle, and P. Ngoepe, “Structure of Surface Entrance Sites for Li Intercalation into TiO2 Nanoparticles, Nanosheets, and Mesoporous Architectures with Application for Li-Ion Batteries,” Journal of Physical Chemistry C. 2016. link Times cited: 7 Abstract: Power output is central to the viability of a Li-ion battery… read moreAbstract: Power output is central to the viability of a Li-ion battery and is, in part, dependent upon the activation energy barrier associated with Li intercalation/deintercalation into the host lattice (electrode). The lower the energy barrier, the faster the intercalation reaction rate and greater the power. The activation energy is governed by the atomistic structure(s) of the entrance sites for Li intercalation. Accordingly, a first step in optimizing battery power via structural manipulation of entrance sites is to understand the structure of these entrance sites. However, HRTEM is (presently) unable to characterize the structures of entrance sites with atomistic resolution. Accordingly, we generate models of the entrance sites using molecular dynamics. In particular, we simulate the synthetic protocol used to fabricate nanostructured TiO2 experimentally. The resulting atomistic models reveal a highly complex and diverse structural distribution of entrance sites, which emanate from the surface curvature of th... read less NOT USED (high confidence) P. Shamberger, J. Wohlwend, A. Roy, and A. Voevodin, “Investigating Grain Boundary Structures and Energetics of Rutile with Reactive Molecular Dynamics,” Journal of Physical Chemistry C. 2016. link Times cited: 4 Abstract: Determining quantitative grain boundary (GB) energies as a f… read moreAbstract: Determining quantitative grain boundary (GB) energies as a function of microscopic orientation parameters is essential in order to understand the population of boundaries present in polycrystalline ceramics and films, and the physical properties that result from these boundaries. Here, we investigate the use of two reactive potentials, COMB3 and ReaxFF, to predict free surface and grain boundary structures and energies in the TiO2 rutile system, and compare these results against previously reported ab initio surface and interfacial energies. We demonstrate reactive MD potentials to be generally capable of reproducing key features anticipated for GB structures and energetics, including relative GB and surface energy, charge distributions and potential for different polar and nonpolar terminations, and energy cusps at low-energy interfaces (e.g., coherent twin boundaries, coherent site lattice boundaries). This work establishes the foundation for further use of reactive MD to simulate libraries of oxide GBs... read less NOT USED (high confidence) G. Okeke, R. Hammond, and S. Antony, “Effects of heat treatment on the atomic structure and surface energy of rutile and anatase TiO2 nanoparticles under vacuum and water environments,” Chemical Engineering Science. 2016. link Times cited: 14 NOT USED (high confidence) H. Nada, M. Kobayashi, and M. Kakihana, “Anisotropy in Conformation and Dynamics of a Glycolate Ion Near the Surface of a TiO2 Rutile Crystal Between Its 001 and 110 Planes: A Molecular Dynamics Study,” Journal of Physical Chemistry C. 2016. link Times cited: 11 Abstract: A molecular dynamics simulation was conducted to elucidate t… read moreAbstract: A molecular dynamics simulation was conducted to elucidate the conformation and dynamics of a glycolate ion (CH2(OH)COO–) at the surface of a TiO2 rutile crystal. The simulation was performed for the {001} and {110} planes of the crystal. The results indicate that, for both planes, the conformation and dynamics of the ion are strongly dominated by a layered structure of water on the surface. The simulation suggests that the ion binds to the surface more stably on the {110} plane than on the {001} plane, and that the stable conformation of the ion at the surface differs between the planes: on the {110} plane the carboxyl group of the ion is preferentially oriented toward the surface, whereas on the {001} plane it is oriented toward liquid water. These simulation results are compared with the growth shapes of rutile crystals synthesized in the presence of glycolic acid, and the role of glycolate ions in controlling the morphology of rutile crystals is discussed. read less NOT USED (high confidence) Y. Xu, M. Wang, N. Hu, J. Bell, and C. Yan, “Atomistic investigation into the mechanical behaviour of crystalline and amorphous TiO2 nanotubes,” RSC Advances. 2016. link Times cited: 10 Abstract: Titanium dioxide (TiO2) nanotubes are appealing to research … read moreAbstract: Titanium dioxide (TiO2) nanotubes are appealing to research communities due to their excellent functional properties. However, there is still a lack of understanding of their mechanical properties. In this work, we conduct molecular dynamics (MD) simulations to investigate the mechanical behaviour of rutile and amorphous TiO2 nanotubes. The results indicate that the rutile TiO2 nanotube has a much higher Young's modulus (∼800 GPa) than the amorphous one (∼400 GPa). Under tensile loading, rutile nanotubes fail in the form of brittle fracture but significant ductility (up to 30%) has been observed in amorphous nanotubes. This is attributed to a unique ‘repairing’ mechanism via bond reconstruction at under-coordinated sites as well as bond conversion at over-coordinated sites. In addition, it is observed that the fracture strength of rutile nanotubes is strongly dependent on their free surfaces. These findings are considered to be useful for development of TiO2 nanostructures with improved mechanical properties. read less NOT USED (high confidence) M. Ozboyaci, D. Kokh, S. Corni, and R. Wade, “Modeling and simulation of protein–surface interactions: achievements and challenges,” Quarterly Reviews of Biophysics. 2016. link Times cited: 128 Abstract: Understanding protein–inorganic surface interactions is cent… read moreAbstract: Understanding protein–inorganic surface interactions is central to the rational design of new tools in biomaterial sciences, nanobiotechnology and nanomedicine. Although a significant amount of experimental research on protein adsorption onto solid substrates has been reported, many aspects of the recognition and interaction mechanisms of biomolecules and inorganic surfaces are still unclear. Theoretical modeling and simulations provide complementary approaches for experimental studies, and they have been applied for exploring protein–surface binding mechanisms, the determinants of binding specificity towards different surfaces, as well as the thermodynamics and kinetics of adsorption. Although the general computational approaches employed to study the dynamics of proteins and materials are similar, the models and force-fields (FFs) used for describing the physical properties and interactions of material surfaces and biological molecules differ. In particular, FF and water models designed for use in biomolecular simulations are often not directly transferable to surface simulations and vice versa. The adsorption events span a wide range of time- and length-scales that vary from nanoseconds to days, and from nanometers to micrometers, respectively, rendering the use of multi-scale approaches unavoidable. Further, changes in the atomic structure of material surfaces that can lead to surface reconstruction, and in the structure of proteins that can result in complete denaturation of the adsorbed molecules, can create many intermediate structural and energetic states that complicate sampling. In this review, we address the challenges posed to theoretical and computational methods in achieving accurate descriptions of the physical, chemical and mechanical properties of protein-surface systems. In this context, we discuss the applicability of different modeling and simulation techniques ranging from quantum mechanics through all-atom molecular mechanics to coarse-grained approaches. We examine uses of different sampling methods, as well as free energy calculations. Furthermore, we review computational studies of protein–surface interactions and discuss the successes and limitations of current approaches. read less NOT USED (high confidence) A. Hosseini et al., “Exosome-inspired targeting of cancer cells with enhanced affinity.,” Journal of materials chemistry. B. 2016. link Times cited: 10 Abstract: One of the major challenges in the area of novel drug delive… read moreAbstract: One of the major challenges in the area of novel drug delivery systems (NDDSs) is finding distinguished ligands for specific receptors represented by many cancer cells in order to enhance their cancer homing efficacy. Exosomes, the so-called natural nanocarriers or "Trojan horses," are secreted by the majority of cancer cells. These carriers exchange biomolecular information (e.g. proteins, siRNA, enzymes) between cancer cells and their stromal compartments in order to adjust a variety of cellular behaviours, including metastasis, apoptosis in T cells and angiogenesis. By exhibiting exosomal smart functions and biomimetic traits, exosome-mimicking nanocarriers will be one step ahead of the conventional targeted DDSs for the efficient delivery of antitumor drugs. In the present study, we tried to describe an engineering route to make some surface-functionalized nanoparticles that can mimic the targeting mechanism recruited by tumor-derived exosomes. The ligand-receptor interactions were investigated by molecular dynamics (MD) simulations. In addition, the selected ligand was experimentally studied to verify its improved targeting efficacy. The present study describes a novel targeting method that forces the mucin-domain-containing molecule-4 (TIM4)-embellished nanoparticles (NPs) to swarm towards the cancerous cells. These NPs can interact with the phosphatidylserine (PS) receptor on the surface of several kinds of cancer cells, such as U-87 MG (glioblastoma cell line). The molecular affinity between TIM4 as a homing device and PS, the target receptor, was investigated using MD simulations and surface plasmon resonance (SPR). According to the calculated free energies and the cellular uptake of TIM4-functionalized NPs, it seems that the TIM4/PS complex releases enough free energy to induce endocytosis. Our results emphasize on the potential of the proposed ligand as a good candidate for many targeted drug delivery applications. In this report, we present our proof-of-concept results in order to spotlight the importance of using computer-based simulating methods at the molecular level for the next-generation nanomedicine. read less NOT USED (high confidence) A. Barnard, “Challenges in modelling nanoparticles for drug delivery,” Journal of Physics: Condensed Matter. 2016. link Times cited: 22 Abstract: Although there have been significant advances in the fields … read moreAbstract: Although there have been significant advances in the fields of theoretical condensed matter and computational physics, when confronted with the complexity and diversity of nanoparticles available in conventional laboratories a number of modeling challenges remain. These challenges are generally shared among application domains, but the impacts of the limitations and approximations we make to overcome them (or circumvent them) can be more significant one area than another. In the case of nanoparticles for drug delivery applications some immediate challenges include the incompatibility of length-scales, our ability to model weak interactions and solvation, the complexity of the thermochemical environment surrounding the nanoparticles, and the role of polydispersivity in determining properties and performance. Some of these challenges can be met with existing technologies, others with emerging technologies including the data-driven sciences; some others require new methods to be developed. In this article we will briefly review some simple methods and techniques that can be applied to these (and other) challenges, and demonstrate some results using nanodiamond-based drug delivery platforms as an exemplar. read less NOT USED (high confidence) Q. Mao, Y. Ren, K. Luo, and S. Li, “Sintering-Induced Phase Transformation of Nanoparticles: A Molecular Dynamics Study,” Journal of Physical Chemistry C. 2015. link Times cited: 25 Abstract: Sintering-induced phase transformation of TiO2 nanoparticles… read moreAbstract: Sintering-induced phase transformation of TiO2 nanoparticles is investigated systematically via molecular dynamics simulation. Upon defining a coordination number and bond angle distribution criteria, local phase information is identified for each individual Ti atom originating from amorphous or crystal structure as well as three TiO2 polymorphs, anatase, brookite, and rutile. Size-dependent structures of nanoparticles lead to different dynamics of the sintering-induced phase transformation. Grain boundaries that form between nanoparticles during sintering trigger the nucleation and growth of new phases. During the sintering of two equal-sized core–shell anatase nanoparticles, crystal core regions melt with the temperature increase and the surface energy decrease in the microcanonical (NVE) ensemble. The new phase that develops from the grain boundary spreads into the destroyed core regions in stages, forming a new larger spherical nanoparticle with an ordered atomic arrangement. During the sintering of t... read less NOT USED (high confidence) C. Arrouvel, T. C. Peixoto, M. Valerio, and S. C. Parker, “Lithium migration at low concentration in TiO2 polymorphs,” Computational and Theoretical Chemistry. 2015. link Times cited: 14 NOT USED (high confidence) X.-jie Zhang and Z. Liu, “Variable-cell double-ended surface walking method for fast transition state location of solid phase transitions.,” Journal of chemical theory and computation. 2015. link Times cited: 48 Abstract: To identify the low energy pathway for solid-to-solid phase … read moreAbstract: To identify the low energy pathway for solid-to-solid phase transition has been a great challenge in physics and material science. This work develops a new theoretical method, namely, variable-cell double-ended surface walking (VC-DESW) to locate the transition state (TS) and deduce the pathway in solid phase transition. Inherited from the DESW method ( J. Chem. Theory Comput. 2013 , 9 , 5745 ) for molecular systems, the VC-DESW method implements an efficient mechanism to couple the lattice and atom degrees of freedom. The method features with fast pseudopathway building and accurate TS location for solid phase transition systems without requiring expensive Hessian computation and iterative pathway optimization. A generalized coordinate, consisting of the lattice vectors and the scaled atomic coordinates, is designed for describing the crystal potential energy surface (PES), which is able to capture the anisotropic behavior in phase transition. By comparing with the existing method for solid phase transition in different systems, we show that the VC-DESW method can be much more efficient for finding the TS in crystal phase transition. With the combination of the recently developed unbiased stochastic surface walking pathway sampling method, the VC-DESW is further utilized to resolve the lowest energy pathway of SiO2 α-quartz to quartz-II phase transition from many likely reaction pathways. These new methods provide a powerful platform for understanding and predicting the solid phase transition mechanism and kinetics. read less NOT USED (high confidence) D. Corradini, Y. Ishii, N. Ohtori, and M. Salanne, “DFT-based polarizable force field for TiO2 and SiO2,” Modelling and Simulation in Materials Science and Engineering. 2015. link Times cited: 9 Abstract: TiO2 and SiO2 are materials with unique importance in materi… read moreAbstract: TiO2 and SiO2 are materials with unique importance in materials science. They are often modelled using conventional force fields, but including polarization effects is compulsory for enhancing the accuracy of the simulations. Here we parameterize a force field for the two materials in the framework of the polarizable ion model. The parameterization is performed via a generalized force-fitting methodology using DFT calculations as reference data. We show that it is possible to generate a force field in which the same parameters are used for the oxide ion in both SiO2 and TiO2, and which is able to reproduce accurately the equilibrium structure of their various crystalline polymorphs, as well as glassy silica. read less NOT USED (high confidence) F. Sen et al., “Towards accurate prediction of catalytic activity in IrO2 nanoclusters via first principles-based variable charge force field,” Journal of Materials Chemistry. 2015. link Times cited: 54 Abstract: IrO2 is one of the most efficient electrocatalysts for the o… read moreAbstract: IrO2 is one of the most efficient electrocatalysts for the oxygen evolution reaction (OER), and also has other applications such as in pH sensors. Atomistic modeling of IrO2 is critical for understanding the structure, chemistry, and nanoscale dynamics of IrO2 in these applications. Such modeling has remained elusive due to the lack of an empirical force field (EFF) for IrO2. We introduce a first-principles-based EFF that couples the Morse (MS) potential with a variable charge equilibration method, QEq. The EFF parameters are optimized using a genetic algorithm (GA) on a density functional theory (DFT)-based training set. The resultant Morse plus QEq EFF, “MS-Q” in short, successfully reproduces the lattice parameters, elastic constants, binding energies, and internal coordinates of various polymorphs of IrO2 from DFT calculations. More importantly, MS-Q accurately captures key metrics for evaluating structural and chemical properties of catalysts such as surface energetics, equilibrium shape, electrostatic charges, oxygen vacancy formation energies, relative stability of low index rutile IrO2 surfaces, and pressure-induced phase transformations. The MS-Q EFF is used to predict the oxygen binding energy (Ead), a well-known descriptor for OER activity, on various sites of a nanocatalyst. We find Ead to be more favorable at low coordination sites, i.e. edges and corners, compared to planar facets; Ead is also correlated with charge transfer between the adsorbed O and nanocrystal, highlighting the importance of variable charge electrostatics in modeling catalysis on metal oxide surfaces. Our variable charge force field offers encouraging prospects for carrying out large-scale reactive simulations to evaluate catalytic performance of IrO2 surfaces and nanostructures. read less NOT USED (high confidence) E. G. Brandt and A. Lyubartsev, “Systematic Optimization of a Force Field for Classical Simulations of TiO2-Water Interfaces,” Journal of Physical Chemistry C. 2015. link Times cited: 47 Abstract: Atomistic force field parameters were developed for the TiO2… read moreAbstract: Atomistic force field parameters were developed for the TiO2–water interface by systematic optimization with respect to experimentally determined crystal structures (lattice parameters) and surface thermodynamics (water adsorption enthalpy). Optimized force field parameters were determined for the two cases where TiO2 was modeled with or without covalent bonding. The nonbonded TiO2 model can be used to simulate different TiO2 phases, while the bonded TiO2 model is particularly useful for simulations of nanosized TiO2 and biomatter, including protein–surface and nanoparticle–biomembrane simulations. The procedure is easily generalized to parametrize interactions between other inorganic surfaces and biomolecules. read less NOT USED (high confidence) Q. Mao and K. Luo, “Molecular Dynamics Simulation of Sintering Dynamics of Many TiO$_2$2 Nanoparticles,” Journal of Statistical Physics. 2015. link Times cited: 10 NOT USED (high confidence) E. Javon et al., “Competing Forces in the Self-Assembly of Coupled ZnO Nanopyramids.,” ACS nano. 2015. link Times cited: 20 Abstract: Self-assembly (SA) of nanostructures has recently gained inc… read moreAbstract: Self-assembly (SA) of nanostructures has recently gained increasing interest. A clear understanding of the process is not straightforward since SA of nanoparticles is a complex multiscale phenomenon including different driving forces. Here, we study the SA between aluminum doped ZnO nanopyramids into couples by combining inorganic chemistry and advanced electron microscopy techniques with atomistic simulations. Our results show that the SA of the coupled nanopyramids is controlled first by morphology, as coupling only occurs in the case of pyramids with well-developed facets of the basal planes. The combination of electron microscopy and atomistic modeling reveals that the coupling is further driven by strong ligand-ligand interaction between the bases of the pyramids as dominant force, while screening effects due to Al doping or solvent as well as core-core interaction are only minor contributions. Our combined approach provides a deeper understanding of the complex interplay between the interactions at work in the coupled SA of ZnO nanopyramids. read less NOT USED (high confidence) C. Shang, W.-N. Zhao, and Z. Liu, “Searching for new TiO2 crystal phases with better photoactivity,” Journal of Physics: Condensed Matter. 2015. link Times cited: 25 Abstract: Using the recently developed stochastic surface walking glob… read moreAbstract: Using the recently developed stochastic surface walking global optimization method, this work explores the potential energy surface of TiO2 crystals aiming to search for likely phases with higher photocatalytic activity. Five new phases of TiO2 are identified and the lowest energy phase transition pathways connecting to the most abundant phases (rutile and anatase) are determined. Theory shows that a high-pressure phase, α-PbO2-like form (TiO2II) acts as the key intermediate in between rutile and anatase. The phase transition of anatase to rutile belongs to the diffusionless Martensitic phase transition, occurring through a set of habit planes, rutile(101)//TiO2II(001), and TiO2II(100)//anatase(112). With regard to the photocatalytic activity, three pure phases (#110, pyrite and fluorite) are found to possess the band gap narrower than rutile, but they are unstable at the low-pressure condition. Instead, a mixed anatase-TiO2II phase is found to have good stability and narrower band gap than both parent phases. Because of the phase separation, the mixed phase is also expected to improve the photocatalytic performance by reducing the probability of the electron-hole pair recombination. read less NOT USED (high confidence) K. Fichthorn, “Atomic-scale aspects of oriented attachment,” Chemical Engineering Science. 2015. link Times cited: 23 NOT USED (high confidence) H. Yildirim, J. Greeley, and S. Sankaranarayanan, “localized order-disorder transitions induced by Li segregation in amorphous TiO2 nanoparticles.,” ACS applied materials & interfaces. 2014. link Times cited: 6 Abstract: Li segregation and transport characteristics in amorphous Ti… read moreAbstract: Li segregation and transport characteristics in amorphous TiO2 nanoparticles (NPs) are studied using molecular dynamics (MD) simulations. A strong intraparticle segregation of Li is observed, and the degree of segregation is found to correlate with Li concentration. With increasing Li concentration, Li diffusivity and segregation are enhanced, and this behavior is tied to the structural response of the NPs with increasing lithiation. The atoms in the amorphous NPs undergo rearrangement in the regions of high Li concentration, introducing new pathways for Li transport and segregation. These localized atomic rearrangements, in turn, induce preferential crystallization near the surfaces of the NPs. Such rich, dynamical responses are not expected for crystalline NPs, where the presence of well-defined lattice sites leads to limited segregation and transport at high Li concentrations. The preferential crystallization in the near-surface region in amorphous NPs may offer enhanced stability and fast Li transport for Li-ion battery applications, in addition to having potentially useful properties for other materials science applications. read less NOT USED (high confidence) S. Kerisit, A. Chaka, T. Droubay, and E. Ilton, “Shell Model for Atomistic Simulation of Lithium Diffusion in Mixed Mn/Ti Oxides,” Journal of Physical Chemistry C. 2014. link Times cited: 14 Abstract: Mixed Mn/Ti oxides present attractive physicochemical proper… read moreAbstract: Mixed Mn/Ti oxides present attractive physicochemical properties such as their ability to accommodate Li for application in Li-ion batteries. In this work, atomic parameters for Mn were developed to extend an existing shell model of the Li–Ti–O system and allow simulations of pure and lithiated Mn and mixed Mn/Ti oxide polymorphs. The shell model yielded good agreement with experimentally derived structures (i.e., lattice parameters and interatomic distances) and represented an improvement over existing potential models. The shell model was employed in molecular dynamics (MD) simulations of Li diffusion in the 1 × 1 c-direction channels of LixMn1–yTiyO2 with the rutile structure, where 0 ≤ x ≤ 0.25 and 0 ≤ y ≤ 1. In the infinite dilution limit, the arrangement of Mn and Ti ions in the lattice was found to have a significant effect on the activation energy for Li diffusion in the c channels due to the destabilization of half of the interstitial octahedral sites. Anomalous diffusion was demonstrated for Li ... read less NOT USED (high confidence) S. Zhu, S.-H. Xie, and Z. Liu, “Design and Observation of Biphase TiO2 Crystal with Perfect Junction.,” The journal of physical chemistry letters. 2014. link Times cited: 29 Abstract: Bicrystalline materials have wide applications from silicon … read moreAbstract: Bicrystalline materials have wide applications from silicon chips to photocatalysis, but the controlled synthesis of nanocrytals with ordered phase junction has been challenging, in particular via chemical synesthetic routes. Here, we propose a general strategy to design biphase crystals formed via partial solid-to-solid phase transition with perfect phase junction, e.g., being atomically sharp and built of two particular sets of epitaxially joined planes of the two component phases, and present such an example by designing, synthesizing, and characterizing the interface of two TiO2 phases, namely, TiO2-B/anatase biphase nanocrystals that are obtained conveniently via one-pot chemical synthesis. Our design strategy classifies the common solid-to-solid phase transition into three types that are distinguishable by using the newly developed stochastic surface walking (SSW) method for unbiased pathway sampling. Only Type-I crystal is predicted to possess perfect phase junction, where the phase transition involves one and only one propagation direction featuring single pathway phase transition containing only one elementary kinetic step. The method is applicable for the understanding and the design of heterophase materials via partial phase transition in general. read less NOT USED (high confidence) Y.-T. Cheng, T.-R. Shan, T. Liang, R. Behera, S. Phillpot, and S. Sinnott, “A charge optimized many-body (comb) potential for titanium and titania,” Journal of Physics: Condensed Matter. 2014. link Times cited: 33 Abstract: This work proposes an empirical, variable charge potential f… read moreAbstract: This work proposes an empirical, variable charge potential for Ti and TiO2 systems based on the charge-optimized many-body (COMB) potential framework. The parameters of the potential function are fit to the structural and mechanical properties of the Ti hcp phase, the TiO2 rutile phase, and the energetics of polymorphs of both Ti and TiO2. The relative stabilities of TiO2 rutile surfaces are predicted and compared to the results of density functional theory (DFT) and empirical potential calculations. The transferability of the developed potential is demonstrated by determining the adsorption energy of Cu clusters of various sizes on the rutile TiO2(1 1 0) surface using molecular dynamics simulations. The results indicate that the adsorption energy is dependent on the number of Cu–Cu bonds and Cu–O bonds formed at the Cu/TiO2 interface. The adsorption energies of Cu clusters on the reduced and oxidized TiO2(1 1 0) surfaces are also investigated, and the COMB potential predicts enhanced bonding between Cu clusters and the oxidized surface, which is consistent with both experimental observations and the results of DFT calculations for other transition metals (Au and Ag) on this oxidized surface. read less NOT USED (high confidence) S. Wallace and K. McKenna, “Grain Boundary Controlled Electron Mobility in Polycrystalline Titanium Dioxide,” Advanced Materials Interfaces. 2014. link Times cited: 52 Abstract: DOI: 10.1002/admi.201400078 devices has been proposed as ess… read moreAbstract: DOI: 10.1002/admi.201400078 devices has been proposed as essential to the switching mechanism. [ 5 ] Despite its importance for these numerous applications defi nitive information on the electron trapping properties of grain boundaries in TiO 2 is still lacking. First principles theoretical calculations can be invaluable to provide insight into electron trapping effects in oxide materials. [ 11–13 ] Many theoretical investigations performed within the framework of density functional theory (DFT) have studied electron trapping in TiO 2 , including bulk crystals (both rutile and anatase polymorphs), surfaces and point defects. [ 11,12,14 ] read less NOT USED (high confidence) C. Shang, X.-jie Zhang, and Z. Liu, “Stochastic surface walking method for crystal structure and phase transition pathway prediction.,” Physical chemistry chemical physics : PCCP. 2014. link Times cited: 89 Abstract: The determination of crystal structures and the solid-to-sol… read moreAbstract: The determination of crystal structures and the solid-to-solid phase transition mechanisms are two important and related subjects in material science. Here we develop an unbiased general-purpose potential energy surface (PES) searching method, namely, SSW-crystal method, for prediction of both the crystal structure and the crystal phase transition pathway. The SSW-crystal method features with stochastic surface walking (SSW) via repeated small structural perturbation by taking into account the second derivative information on both the lattice and the atom degrees of freedom. The SSW-crystal method is capable of overcoming the high barrier of phase transition and identifying the desirable phase transition reaction coordinates. By applying the SSW-crystal method to a set of examples, including SiO2 crystal up to 162 atoms per cell, Lennard-Jones model crystals up to 256 atoms, ternary SrTiO3 crystal of 50 atoms and the rutile-to-anatase TiO2 phase transition, we show that the SSW-crystal method can efficiently locate the global minimum (GM) from random initial structures without a priori knowledge of the system, and also allows for exhaustive sampling of the phase transition pathways, from which the lowest energy pathway can be obtained. read less NOT USED (high confidence) W. Friedrichs and W. Langel, “Atomistic modeling of peptide adsorption on rutile (100) in the presence of water and of contamination by low molecular weight alcohols.,” Biointerphases. 2014. link Times cited: 9 Abstract: Previous models for the interface between titanium implants … read moreAbstract: Previous models for the interface between titanium implants and biosystems take into account the oxide passivation layer and the hydroxylation, but omit the hydrocarbon contamination on air-exposed samples. The authors develop a consistent model for the contamination of the rutile (100) surface by small alcohols, which are known to be present in ambient atmosphere, and use this approach in molecular dynamics calculations. Contact angle evaluation reveals that hydrophobic surfaces can be generated. During molecular dynamics simulations with three peptides (RPRGFGMSRERQ, WFCLLGCDAGCW, and RKLPDA), polar side chains penetrate the hydrocarbons and become immobilized on the titanium dioxide. In the carbon layer, the peptide recognizes a hydrophobic environment, which was not present on the clean surface, and the authors attribute changes in the secondary structure in one case to this interaction. The authors further include the popular Matsui-Akaogi approach [M. Matsui and M. Akaogi, Mol. Simul. 6, 239 (1991)] into the frame of the AMBER force field and quote van der Waals parameters for fitting the original Buckingham part. With the new potential, the authors evaluated lattice parameters, thermal fluctuation, and bulk modulus. Translational diffusion coefficients and dipole autocorrelation functions of water on the surface are discussed in relation to surface properties, and it is shown that the water layers are more rigid than on earlier titanium dioxide models, and that contacts between peptide and surface are less direct. read less NOT USED (high confidence) F. D. Angelis, C. D. Valentin, S. Fantacci, A. Vittadini, and A. Selloni, “Theoretical studies on anatase and less common TiO2 phases: bulk, surfaces, and nanomaterials.,” Chemical reviews. 2014. link Times cited: 348 Abstract: Surfaces, and Nanomaterials Filippo De Angelis,† Cristiana D… read moreAbstract: Surfaces, and Nanomaterials Filippo De Angelis,† Cristiana Di Valentin,‡ Simona Fantacci,† Andrea Vittadini, and Annabella Selloni* †Computational Laboratory for Hybrid Organic Photovoltaics (CLHYO), Istituto CNR di Scienze e Tecnologie Molecolari, Via Elce di Sotto 8, I-06123 Perugia, Italy ‡Dipartimento di Scienza dei Materiali, Universita ̀ di Milano-Bicocca, I-20125 Milano, Italy Istituto CNR per l’Energetica e le Interfasi (IENI), c/o Dipartimento di Scienze Chimiche, Universita’ di Padova, I-35131 Padova, Italy Department of Chemistry, Princeton University, Princeton, New Jersey 08544, United States read less NOT USED (high confidence) M. Landmann, T. Köhler, E. Rauls, T. Frauenheim, and W. Schmidt, “The atomic structure of ternary amorphous TixSi1−xO2 hybrid oxides,” Journal of Physics: Condensed Matter. 2014. link Times cited: 10 Abstract: Atomic length-scale order characteristics of binary and tern… read moreAbstract: Atomic length-scale order characteristics of binary and ternary amorphous oxides are presented within the framework of ab initio theory. A combined numerically efficient density functional based tight-binding molecular dynamics and density functional theory approach is applied to model the amorphous (a) phases of SiO2 and TiO2 as well as the amorphous phase of atomically mixed TixSi1−xO2 hybrid-oxide alloys over the entire composition range. Short and mid-range order in the disordered material phases are characterized by bond length and bond-angle statistics, pair distribution function analysis, coordination number and coordination polyhedra statistics, as well as ring statistics. The present study provides fundamental insights into the order characteristics of the amorphous hybrid-oxide frameworks formed by versatile types of TiOn and SiOm coordination polyhedra. In a-SiO2 the fourfold crystal coordination of Si ions is almost completely preserved and the atomic structure is widely dominated by ring-like mid-range order characteristics. In contrast, the structural disorder of a-TiO2 arises from short-range disorder in the local coordination environment of the Ti ion. The coordination number analysis indicates a large amount of over and under-coordinated Ti ions (coordination defects) in a-TiO2. Aside from the ubiquitous distortions of the crystal-like coordinated polyhedra, even the basic coordination-polyhedra geometry type changes for a significant fraction of TiO6 units (geometry defects). The combined effects of topological and chemical disorder in a-TixSi1−xO2 alloys lead to a continuos increase in both the Si as well as the Ti coordination number with the chemical composition x. The important roles of intermediate fivefold coordination states of Ti and Si cations are highlighted for ternary a-TixSi1−xO2 as well as for binary a-TiO2. The continuous decrease in ring size with increasing Ti content reflects the progressive loss of mid-range order structure characteristics and the competing roles of network forming and network modifying SiOm and TiOn units in the mixed hybrid oxides. read less NOT USED (high confidence) O. V. Artoshina, M. Vorob’eva, E. Dushanov, and K. Kholmurodov, “Molecular dynamics simulations of formamide interaction with hydrocyanic acid on a catalytic surface TiO2,” Russian Journal of Physical Chemistry A. 2014. link Times cited: 2 NOT USED (high confidence) Y. G. Andreev, P. M. Panchmatia, Z. Liu, S. C. Parker, M. S. Islam, and P. G. Bruce, “The shape of TiO₂-B nanoparticles.,” Journal of the American Chemical Society. 2014. link Times cited: 26 Abstract: The shape of nanoparticles can be important in defining thei… read moreAbstract: The shape of nanoparticles can be important in defining their properties. Establishing the exact shape of particles is a challenging task when the particles tend to agglomerate and their size is just a few nanometers. Here we report a structure refinement procedure for establishing the shape of nanoparticles using powder diffraction data. The method utilizes the fundamental formula of Debye coupled with a Monte Carlo-based optimization and has been successfully applied to TiO2-B nanoparticles. Atomistic modeling and molecular dynamics simulations of ensembles of all the ions in the nanoparticle reveal surface hydroxylation as the underlying reason for the established shape and structural features. read less NOT USED (high confidence) D. Corradini, D. Dambournet, and M. Salanne, “Tuning the Electronic Structure of Anatase Through Fluorination,” Scientific Reports. 2014. link Times cited: 13 NOT USED (high confidence) M. Saba and A. Mattoni, “Effect of Thermodynamics and Curvature on the Crystallinity of P3HT Thin Films on ZnO: Insights from Atomistic Simulations,” Journal of Physical Chemistry C. 2014. link Times cited: 10 Abstract: In this work, by means of model potential molecular dynamics… read moreAbstract: In this work, by means of model potential molecular dynamics simulations, we correlate the polymer crystalline order to the substrate morphology by focusing on the case of thin P3HT films deposited on planar and nanostructured ZnO surfaces under room temperature conditions. We show that the polymer/ZnO adhesion is driven by the electrostatic interactions between backbones and substrates. On planar ZnO substrates, though some disorder is present, the polymer films can be crystalline with predominance of the face-on molecular orientation. In addition, by studying models of curved substrates, consisting of ZnO nanorods, we show that the local curvature induces the bending of the polymer backbones and consequent disorder in the molecular film with the possible formation of amorphous layers. The analysis of the structure factor reveals a monotonic correlation between the local curvature and the diffraction peak associated with the backbone. read less NOT USED (high confidence) S. G. Neogi and P. Chaudhury, “Structural, spectroscopic aspects, and electronic properties of (TiO2)n clusters: A study based on the use of natural algorithms in association with quantum chemical methods,” Journal of Computational Chemistry. 2014. link Times cited: 32 Abstract: In this article, we propose a stochastic search‐based method… read moreAbstract: In this article, we propose a stochastic search‐based method, namely genetic algorithm (GA) and simulated annealing (SA) in conjunction with density functional theory (DFT) to evaluate global and local minimum structures of (TiO2)n clusters with n = 1–12. Once the structures are established, we evaluate the infrared spectroscopic modes, cluster formation energy, vertical excitation energy, vertical ionization potential, vertical electron affinity, highest occupied molecular orbital (HOMO)‐lowest unoccupied molecular orbital (LUMO) gaps, and so forth. We show that an initial determination of structure using stochastic techniques (GA/SA), also popularly known as natural algorithms as their working principle mimics certain natural processes, and following it up with density functional calculations lead to high‐quality structures for these systems. We have shown that the clusters tend to form three‐dimensional networks. We compare our results with the available experimental and theoretical results. The results obtained from SA/GA‐DFT technique agree well with available theoretical and experimental data of literature. © 2013 Wiley Periodicals, Inc. read less NOT USED (high confidence) E. Dushanov, K. Kholmurodov, and K. Yasuoka, “Structural and diffusion properties of formamide/water mixture interacting with TiO2 surface.,” Bioorganic chemistry. 2013. link Times cited: 2 NOT USED (high confidence) S. Walia et al., “Transition metal oxides – Thermoelectric properties,” Progress in Materials Science. 2013. link Times cited: 297 NOT USED (high confidence) R. Darkins, M. Sushko, J. Liu, and D. Duffy, “Adhesion of sodium dodecyl sulfate surfactant monolayers with TiO(2) (rutile and anatase) surfaces.,” Langmuir : the ACS journal of surfaces and colloids. 2013. link Times cited: 10 Abstract: Surfactants are widely used as templates to control the nucl… read moreAbstract: Surfactants are widely used as templates to control the nucleation and growth of nanostructured metal oxides such as titania. To gain insight into the origin of the surfactant-titania interactions responsible for polymorph and orientation selection, we simulate the self-assembly of an anionic surfactant monolayer on various low-index titania surfaces, for a range of densities. We characterize the binding in each case and compute the adhesion energies, finding anatase (100) and rutile (110) to be the strongest-binding surfaces. The sodium counterions in the monolayer are found to dominate the adhesion. It is also observed that the assembly is directed predominantly by surface-monolayer electrostatic complementarity. Incorporating water displacement into the calculations does not alter the general findings but does cause the adhesion energies to fall within a smaller range. read less NOT USED (high confidence) M. Qin et al., “Density and structural effects in the radiation tolerance of TiO2 polymorphs,” Journal of Physics: Condensed Matter. 2013. link Times cited: 12 Abstract: The radiation response of TiO2 has been studied using molecu… read moreAbstract: The radiation response of TiO2 has been studied using molecular dynamics. The simulations are motivated by experimental observations that the three low-pressure polymorphs, rutile, brookite and anatase, exhibit vastly different tolerances to amorphization under ion-beam irradiation. To understand the role of structure we perform large numbers of simulations using the small thermal spike method. We quantify to high statistical accuracy the number of defects created as a function of temperature and structure type, and reproduce all the main trends observed experimentally. To evaluate a hypothesis that volumetric strain relative to the amorphous phase is an important driving force for defect recovery, we perform spike simulations in which the crystalline density is varied over a wide range. Remarkably, the large differences between the polymorphs disappear once the density difference is taken into account. This finding demonstrates that density is an important factor which controls radiation tolerance in TiO2. read less NOT USED (high confidence) T. Köhler, M. Turowski, H. Ehlers, M. Landmann, D. Ristau, and T. Frauenheim, “Computational approach for structure design and prediction of optical properties in amorphous TiO2 thin-film coatings,” Journal of Physics D: Applied Physics. 2013. link Times cited: 26 Abstract: We have investigated the structural and electronic propertie… read moreAbstract: We have investigated the structural and electronic properties of amorphous TiO2 using molecular dynamics (MD) simulations based on ab initio density functional theory, a numerically efficient density-functional-based tight-binding approach and classical many-body potentials. The lower level approximations are successively validated by the higher level ones through comparison of the calculated structural and electronic properties. The classical results reproduce all relevant structural features of a-TiO2 as obtained by quantum-mechanical simulation and reproduce the experimentally observed reduced radial distribution function. This gives convincing justification for the use of classical MD in the simulation of ion beam sputtering synthesis of large-area amorphous thin films. Cross-correlation of electronic data with the statistics of disorder-induced under- and over-coordination is derived as a basis for evaluating the optical quality of thin-film coatings. read less NOT USED (high confidence) T. P. M. Goumans and S. T. Bromley, “Stardust silicate nucleation kick-started by SiO+TiO2,” Philosophical Transactions of the Royal Society A: Mathematical, Physical and Engineering Sciences. 2013. link Times cited: 16 Abstract: Dust particles are quintessential for the chemical evolution… read moreAbstract: Dust particles are quintessential for the chemical evolution of the Universe. Dust nucleates in stellar outflows of dying stars and subsequently travels through the interstellar medium, continuously evolving via energetic processing, collisions and condensation. Finally, dust particles are incorporated in the next-generation star or its surrounding planetary system. In oxygen-rich stellar outflows, silicates are observed in the condensation zone (1200–1000 K), but, in spite of several decades of experimental and theoretical study, the stardust nucleation process remains poorly understood. We have previously shown that under these conditions ternary Mg–Si–O clusters may start forming at high enough rates from SiO, Mg and H2O through heteromolecular association processes. In this reaction scheme, none of the possible initial association reactions was thermodynamically favourable owing to the large entropy loss at these temperatures. Here, we follow a previous idea that the incorporation of TiO2 could help to initiate stardust nucleation. In contrast to these studies, we find that there is no need for TiO2 cluster seeds—instead, one molecule of TiO2 is sufficient to kick-start the subsequent nucleation of a silicate dust particle. read less NOT USED (high confidence) G. Malloci, M. Binda, A. Petrozza, and A. Mattoni, “Role of molecular thermodynamical processes at functionalized polymer/metaloxide interfaces for photovoltaics,” Journal of Physical Chemistry C. 2013. link Times cited: 11 Abstract: We present a combined theoretical and experimental investiga… read moreAbstract: We present a combined theoretical and experimental investigation of the role of pyridine-based functionalizers (IMs) at the hybrid titania (TiO2)/poly(3-hexylthiophene) (P3HT) interface. We first used density functional theory to study the electronic structure and adsorption energy of several IMs, isolated and self-assembled, on a TiO2 anatase (101) surface. Small details in the molecular structure are found to induce strong differences in the morphology of the corresponding self-assembled monolayer. We then used model potential molecular dynamics simulations to study the translational and rotational diffusion of a P3HT oligomer on the naked and functionalized TiO2 surfaces. We correlate the photovoltaic performance measured on TiO2/IM/P3HT with the degree of order of the interface. In particular, we find that the thiol group of 4-mercaptopyridine is able to stabilize the corresponding self-assembled interlayer. This, in turn, increases the polymer mobility on the inorganic surface, yielding a larger poly... read less NOT USED (high confidence) G. Okeke, R. Hammond, and S. J. Antony, “Influence of size and temperature on the phase stability and thermophysical properties of anatase TiO2 nanoparticles: molecular dynamics simulation,” Journal of Nanoparticle Research. 2013. link Times cited: 6 NOT USED (high confidence) V. Fuertes et al., “A theoretical study of the optical properties of nanostructured TiO2,” Journal of Physics: Condensed Matter. 2013. link Times cited: 33 Abstract: Optical properties of TiO2 nanoclusters (with more than 30 T… read moreAbstract: Optical properties of TiO2 nanoclusters (with more than 30 TiO2 units) were calculated within a fully atomistic quantum dynamic framework. We use a time dependent tight-binding model to describe the electronic structure of TiO2 nanoclusters in order to compute their optical properties. We present calculated absorption spectra for a series of nanospheres of different radii and crystal structures. Our results show that bare TiO2 nanoclusters have the same adsorption edge for direct electronic transition independently of the crystal structure and the nanocluster size. We report values of the adsorption edge of around 3.0 eV for all structures analyzed. In the present work we demonstrate that, for small clusters, both the direct transition absorption edge and the blue shifting phenomena are masked by thermal disorder. read less NOT USED (high confidence) E. Andritsos et al., “The heat capacity of matter beyond the Dulong–Petit value,” Journal of Physics: Condensed Matter. 2013. link Times cited: 47 Abstract: We propose a simple new way to evaluate the effect of anharm… read moreAbstract: We propose a simple new way to evaluate the effect of anharmonicity on a system’s thermodynamic functions, such as heat capacity. In this approach, the contribution of all the potentially complicated anharmonic effects to the constant-volume heat capacity is evaluated using one parameter only: the coefficient of thermal expansion. Importantly, this approach is applicable not only to crystals, but also to glasses and viscous liquids. To support this proposal, we perform molecular dynamics simulations of several crystalline and amorphous solids as well as liquids, and find a good agreement between the results from theory and simulations. We observe an interesting non-monotonic behavior of the liquid heat capacity with a maximum, and explain this effect as being a result of competition between anharmonicity at low temperature and decreasing number of transverse modes at high temperature. read less NOT USED (high confidence) H. Yildirim, J. Greeley, and S. Sankaranarayanan, “Concentration-Dependent Ordering of Lithiated Amorphous TiO2,” Journal of Physical Chemistry C. 2013. link Times cited: 17 Abstract: We present the results of molecular dynamics simulations on … read moreAbstract: We present the results of molecular dynamics simulations on the disorder–order transition of highly lithiated amorphous TiO2. Our simulations suggest the presence of a threshold Li concentration ab... read less NOT USED (high confidence) E. G. Solveyra, E. D. L. Llave, V. Molinero, G. J. A. A. Soler-Illia, and D. Scherlis, “Structure, Dynamics, and Phase Behavior of Water in TiO2 Nanopores,” Journal of Physical Chemistry C. 2013. link Times cited: 57 Abstract: Mesoporous titania is a highly studied material due to its e… read moreAbstract: Mesoporous titania is a highly studied material due to its energy and environment-related applications, which depend on its tailored surface and electronic properties. Understanding the behavior of water in titania pores is a central issue for practical purposes in photocatalysis, solar cells, bone implants, or optical sensors. In particular, the mechanisms of capillary condensation of water in titania mesopores and the organization and mobility of water as a function of pore filling fraction are not yet known. In this work, molecular dynamics simulations of water confined in TiO2-rutile pores of diameters 1.3, 2.8, and 5.1 nm were carried out at various water contents. Water density and diffusion coefficients were obtained as a function of the distance from the surface. The proximity to the interface affects density and diffusivity within a distance of around 10 A from the walls, beyond which all properties tend to converge. The densities of the confined liquid in the 2.8 and the 5.1 nm pores decrease, r... read less NOT USED (high confidence) J. Houška, S. Mráz, and J. Schneider, “Experimental and molecular dynamics study of the growth of crystalline TiO2,” Journal of Applied Physics. 2012. link Times cited: 29 Abstract: Thin films of crystalline TiO2 are of high interest due to t… read moreAbstract: Thin films of crystalline TiO2 are of high interest due to their photoactivity and photoinduced hydrophilicity. Previously, preparation of TiO2 has been described in terms of extrinsic process parameters, such as total pressure, oxygen partial pressure, or substrate bias potential. We study the growth of TiO2 phases, rutile and anatase, by atom-by-atom molecular dynamics simulations. We focus on the effect of intrinsic process parameters including particle energy, growth temperature, and growth template. While experiments indicate that the deposition of rutile requires higher temperatures and/or energies compared to anatase, we show that the growth of previously nucleated rutile can take place in a wider range of temperatures and energies compared to anatase. In parallel, we show relationships between crystal growth and the lateral size of a crystal. The results facilitate defining new synthesis pathways for TiO2, and constitute phenomena which may be relevant for other ceramics. read less NOT USED (high confidence) B. Buesser and A. Gröhn, “Multiscale Aspects of Modeling Gas-Phase Nanoparticle Synthesis.,” Chemical engineering & technology. 2012. link Times cited: 25 Abstract: Aerosol reactors are utilized to manufacture nanoparticles i… read moreAbstract: Aerosol reactors are utilized to manufacture nanoparticles in industrially relevant quantities. The development, understanding and scale-up of aerosol reactors can be facilitated with models and computer simulations. This review aims to provide an overview of recent developments of models and simulations and discuss their interconnection in a multiscale approach. A short introduction of the various aerosol reactor types and gas-phase particle dynamics is presented as a background for the later discussion of the models and simulations. Models are presented with decreasing time and length scales in sections on continuum, mesoscale, molecular dynamics and quantum mechanics models. read less NOT USED (high confidence) Y. Zhang, S. Li, W. Yan, and S. Tse, “Effect of size-dependent grain structures on the dynamics of nanoparticle coalescence,” Journal of Applied Physics. 2012. link Times cited: 22 Abstract: The effect of grain structure on the coalescence dynamics of… read moreAbstract: The effect of grain structure on the coalescence dynamics of anatase TiO2 nanoparticles at different temperatures is investigated using classical molecular dynamics (MD) simulation. Examination of local-lattice-orientation distributions reveals that the grain morphology of particles is highly dependent on size. For a single anatase nanoparticle below the melting temperature, an amorphous-to-crystalline transition occurs for diameters ranging from 2 to 2.5 nm as temperature increases. Below the transition diameter (for a given temperature), the entire nanoparticle is amorphous. Above the transition diameter, the nanoparticle consists of a crystalline core and an amorphous shell (4–6 A). Considering that such grain-structure characteristics may lead to different dynamic behaviors, the coalescence between pairs of 2 nm–2 nm, 3 nm–3 nm, and 2 nm–3 nm nanoparticles is investigated. For 2 nm–2 nm nanoparticle coalescence, the process is independent of initial temperature and is seemingly viscosity-controlled wi... read less NOT USED (high confidence) E. Dushanov, K. Kholmurodov, and K. Yasuoka, “The diffusion and concentration effects of formamide on a TiO2 surface in the presence of a water solvent,” Natural Science. 2012. link Times cited: 2 Abstract: The formamide-titanium oxide interaction mechanism is a rese… read moreAbstract: The formamide-titanium oxide interaction mechanism is a research target of great importance for understanding the elementary events of the origin of life: the synthesis of nucleoside bases and formation of biological molecules needed for life. Titanium oxide (TiO2) can act as a strongly adsorbing surface or a catalytic material. In the present study, a comparative molecular dynamics analysis performed to clarify the adsorbing and diffusion properties of liquid formamide on a TiO2 surface in the presence of water molecules. The structural features of the formamide concentration effect (the accumulation of molecules) on a TiO2 surface in the presence and absence of water solvent are cleared up. Modification of the formamide diffusion abilities mediated by a water solvent is observed to correlate with the formamide-water concentration distribution on the surface. read less NOT USED (high confidence) N. J. English, R. Kavathekar, and J. MacElroy, “Hydrogen bond dynamical properties of adsorbed liquid water monolayers with various TiO2 interfaces,” Molecular Physics. 2012. link Times cited: 20 Abstract: Equilibrium classical molecular dynamics (MD) simulations ha… read moreAbstract: Equilibrium classical molecular dynamics (MD) simulations have been performed to investigate the hydrogen-bonding kinetics of water in contact with rutile-(110), rutile-(101), rutile-(100), and anatase-(101) surfaces at room temperature (300 K). It was observed that anatase-(101) exhibits the longest-lived hydrogen bonds in terms of overall persistence, followed closely by rutile-(110). The relaxation times, defined as the integral of the autocorrelation of the hydrogen bond persistence function, were also longer for these two cases, while decay of the autocorrelation function was slower. The increased number and overall persistence of hydrogen bonds in the adsorbed water monolayers at these surfaces, particularly for anatase-(101), may serve to promote possible water photolysis activity thereon. read less NOT USED (high confidence) T. Lan, X. Tang, and B. Fultz, “Phonon anharmonicity of rutile TiO_2 studied by Raman spectrometry and molecular dynamics simulations,” Physical Review B. 2012. link Times cited: 85 Abstract: Raman spectra of rutile titanium dioxide (TiO_2) were measur… read moreAbstract: Raman spectra of rutile titanium dioxide (TiO_2) were measured at temperatures from 100 to 1150 K. Each Raman mode showed unique changes with temperature. Beyond the volume-dependent quasiharmonicity, the explicit anharmonicity was large. A new method was developed to fit the thermal broadenings and shifts of Raman peaks with a full calculation of the kinematics of three-phonon and four-phonon processes, allowing the cubic and quartic components of the anharmonicity to be identified for each Raman mode. A dominant role of phonon-phonon kinematics on phonon shifts and broadenings is reported. Force-field molecular dynamics calculations with the Fourier-transformed velocity autocorrelation method were also used to perform a quantitative study of anharmonic effects, successfully accounting for the anomalous phonon anharmonicity of the B_1_(g) mode. read less NOT USED (high confidence) K. Kaur, S. Prakash, and N. Goyal, “Strained structure of differently prepared amorphous TiO_2 nanoparticle: Molecular dynamics study,” Journal of Materials Research. 2011. link Times cited: 13 Abstract: Matusi-Akaogi force field is used in molecular dynamics simu… read moreAbstract: Matusi-Akaogi force field is used in molecular dynamics simulations to generate three samples of amorphous TiO_2 of 3-nm size under different heating and quenching rates. The averaged pair correlation functions, coordination numbers, bond lengths, bond angles, and dihedral angles are calculated at 315 K. It is found that overcoordinated Ti and O atoms are in the core region, 6- and 3-fold coordinated Ti and O atoms are in the central part, and undercoordinated Ti and O atoms are in the vicinity of the surface. The correlations are significant up to 10 A and vanish at the particle size. The calculated averaged bond lengths for short-range interparticle correlations agree with the experimental data. The discrete bond angles and dihedral angles of crystalline sphere get distributed over complete range in the amorphous phase and closer strained atomic network is predicted. The relative variance in the atomic arrangements in three samples is within 4%. read less NOT USED (high confidence) C. Melis, L. Colombo, and A. Mattoni, “Adhesion and Diffusion of Zinc-Phthalocyanines on the ZnO (101̅0) Surface,” Journal of Physical Chemistry C. 2011. link Times cited: 9 Abstract: We study the adhesion and the diffusion of single zinc-phtha… read moreAbstract: We study the adhesion and the diffusion of single zinc-phthalocyanine (ZnPc) molecules on a ZnO (1010) surface by means of model potential molecular dynamics. We find that the molecule is easily adsorbed on the surface, and we identify the ZnPc adsorption sites. The diffusion at room temperature is studied by metadynamics. We find that the molecule is able to diffuse by hopping between the surface dimer rows along the [010] crystallographic direction with a free energy barrier as small as ∼0.4 eV. At temperatures T > 700 K, a different mechanism is found with large diffusion paths along the surface trench grooves. read less NOT USED (high confidence) O. Syzgantseva, P. González-Navarrete, M. Calatayud, S. Bromley, and C. Minot, “Theoretical Investigation of the Hydrogenation of (TiO2)N Clusters (N = 1–10),” Journal of Physical Chemistry C. 2011. link Times cited: 62 Abstract: We present density functional calculations of H2 adsorption … read moreAbstract: We present density functional calculations of H2 adsorption on small-sized titania clusters for (TiO2)N, N = 1–10. Initial hydrogen atoms easily bind with adsorption energies larger than 10 kcal/mol only to terminal oxygen sites, resulting in a reduction of the titanium sites. The adsorption of a second hydrogen atom is poorly exothermic except on clusters of sizes N = 1, 4, and 8. The most stable hydrogenated cluster structures do not always correspond to those of the most stable naked clusters. The structures, energetics, and spin states of the most stable reduced clusters are explained as a balance of local geometry, orbital energy levels, and ionicity. On a single cluster, a step by step mechanism for H2 dissociation is investigated, proceeding through a hydride intermediate and consecutive migration. The barriers depend on the local environment of the adsorption site and are relatively high compared with the limit of atomic desorption, so other dissociation mechanisms cannot be ruled out. Contrary to... read less NOT USED (high confidence) Y. Zhang, S. Li, W. Yan, Q. Yao, and S. Tse, “Role of dipole-dipole interaction on enhancing Brownian coagulation of charge-neutral nanoparticles in the free molecular regime.,” The Journal of chemical physics. 2011. link Times cited: 40 Abstract: In contrast to van der Waals (vdW) forces, Coulombic dipolar… read moreAbstract: In contrast to van der Waals (vdW) forces, Coulombic dipolar forces may play a significant role in the coagulation of nanoparticles (NPs) but has received little or no attention. In this work, the effect of dipole-dipole interaction on the enhancement of the coagulation of two spherically shaped charge-neutral TiO(2) NPs, in the free molecular regime, is studied using classical molecular dynamics (MD) simulation. The enhancement factor is evaluated by determining the critical capture radius of two approaching NPs for different cases of initial dipole direction with respect to path (parallel∕perpendicular) and orientation with respect to each other (co-orientated∕counterorientated). As particle diameter decreases, the enhancement of coagulation is augmented as the ratio of dipole-dipole force to vdW force becomes larger. For 2-nm TiO(2) NPs at 273 K, the MD simulation predicts an average enhancement factor of about 8.59, which is much greater than the value of 3.78 when only the vdW force is considered. Nevertheless, as temperature increases, the enhancement factor due to dipole-dipole interaction drops quickly because the time-averaged dipole moment becomes small due to increased thermal fluctuations (in both magnitude and direction) of the instantaneous dipole moment. read less NOT USED (high confidence) C. Sun, L. M. Liu, A. Selloni, G. Lu, and S. C. Smith, “Titania-water interactions: a review of theoretical studies,” Journal of Materials Chemistry. 2010. link Times cited: 246 Abstract: The interaction between water (H2O) and titanium dioxide (Ti… read moreAbstract: The interaction between water (H2O) and titanium dioxide (TiO2) has a central role in many environment- and energy-related applications, such as the photodecomposition of organic pollutants, solar cells, and solar-hydrogen production. The importance of these applications has motivated strong interest and intensive experimental and theoretical studies of H2O adsorption on TiO2 surfaces for decades. This review attempts to summarize the major theoretical outcomes on this topic in the last twenty years, ranging from low coverages of adsorbed water molecules up to water multilayers on various TiO2 surfaces. Theoretical/computational methods as well as structural models are discussed and a detailed comparison of the results from various computational settings is presented. The interaction of water with photoexcited TiO2 surfaces is a challenging but very interesting subject for future studies. read less NOT USED (high confidence) C. Wu, M. Chen, and C.-M. Xing, “Molecular understanding of conformational dynamics of a fibronectin module on rutile (110) surface.,” Langmuir : the ACS journal of surfaces and colloids. 2010. link Times cited: 31 Abstract: The conformational dynamics of the 10th type-III module of f… read moreAbstract: The conformational dynamics of the 10th type-III module of fibronectin (FN-III(10)) adsorbed on the perfect and three reduced rutile TiO(2)(110) surfaces with different types of defects was investigated by molecular dynamics (MD) simulations. Stable protein-surface complexes were presented in the four simulated models and were derived from the contributions of direct and indirect interactions of various functional groups in FN-III(10) with the metal oxide layers. A detailed analysis to characterize the overall structural stability of the adsorbed FN-III(10) molecule suggests that the bonding strength and the loss of protein secondary structure vary widely, depending on the topology of the substrate surface. The additional adsorption sites exhibiting higher activity, provided by the reduced surfaces, are responsible for the stronger FN-III(10)-TiO(2) interactions, but too high an interaction energy will cause a severe conformational deformation and therefore a significant loss of bioactivity of the adsorbed protein. read less NOT USED (high confidence) D. Song, M. Chen, Y. Liang, C. Wu, Z. Xie, and Q. Bai, “Molecular dynamics simulation study on surface structure and surface energy of anatase,” Modelling and Simulation in Materials Science and Engineering. 2010. link Times cited: 8 Abstract: Molecular dynamics simulations were performed to investigate… read moreAbstract: Molecular dynamics simulations were performed to investigate the relaxed structures and surface energies of perfect and pit anatase TiO2 surfaces. It is shown that the slab containing more than two unit-cell layers away from the fixed layer expresses the surface characteristics of perfect anatase TiO2 (1 0 1) and (1 0 0) surfaces well, while the slab containing more than one unit-cell layer away from the fixed layer expresses the surface characteristics of the (0 0 1) surface well. Their surface energies follow the sequence (0 0 1) < (1 0 1) < (1 0 0). Simulation results also indicate that the pit edges expose many undercoordinated atoms, and the more highly undercoordinated atoms exhibit the larger displacement vectors. Moreover, the surface energy of the pit surface is higher than that of the perfect surface. The surface energies of pit anatase (1 0 1) surfaces are linearly related to the pit sizes along the [ ] and [0 1 0] directions, and the changes in their surface energies are less than 0.05 J m−2, while the surface energies increase sharply with the increase in pit depth within 1 nm. Therefore, for anatase (1 0 1) surface, in order to obtain a higher surface energy, one may increase the pit sizes, particularly along the [1 0 1] direction. read less NOT USED (high confidence) A. Barnard, “Modelling of nanoparticles: approaches to morphology and evolution,” Reports on Progress in Physics. 2010. link Times cited: 171 Abstract: As we learn more about the physics, chemistry and engineerin… read moreAbstract: As we learn more about the physics, chemistry and engineering of materials at the nanoscale, we find that the development of a complete understanding is not (in general) possible using one technique alone. Computer simulations provide a very valuable addition to our scientific repertoire, but it is not immediately intuitive which of the many methods available are right for a given problem. In this paper, various computational approaches are described as they apply to the study of the structure and formation of discrete inorganic nanoparticles. To illustrate how these methods are best used, results of studies from many research groups are reviewed, and informal case studies are constructed on carbon, titania and gold nanoparticles. read less NOT USED (high confidence) E. Zaminpayma, A. Bahramian, M. Kalbasi, and H. E. Nia, “Computer Simulation on TiO2 Nanostructure Films and Experimental Study Using Sol–Gel Method,” Journal of Cluster Science. 2009. link Times cited: 5 NOT USED (high confidence) N. J. English and W. F. Long, “Estimation of zeta potentials of titania nanoparticles by molecular simulation,” Physica A-statistical Mechanics and Its Applications. 2009. link Times cited: 13 NOT USED (high confidence) N. Baguer, V. Georgieva, L. Calderin, I. Todorov, S. V. Gils, and A. Bogaerts, “Study of the nucleation and growth of TiO2 and ZnO thin films by means of molecular dynamics simulations,” Journal of Crystal Growth. 2009. link Times cited: 25 NOT USED (high confidence) I. Gheewala, R. Smith, and S. Kenny, “Nanoindentation and nanoscratching of rutile and anatase TiO2 studied using molecular dynamics simulations,” Journal of Physics: Condensed Matter. 2008. link Times cited: 20 Abstract: The results of molecular dynamics (MD) simulations of nanoin… read moreAbstract: The results of molecular dynamics (MD) simulations of nanoindentation and nanoscratching of titanium dioxide lattices are presented. The TiO2 surfaces investigated are the (001) and {110} rutile surfaces and the anatase {100} and (001) surfaces. A spring model consisting of a cube cornered indenter connected to supports, via a set of springs, was used to model the cantilever in an atomic force microscope. Indentations were conducted to depths of 12 and 18 Å on each surface and scratching simulations were conducted for a length of 80 Å and at a depth of 6 Å. Pile-up patterns were found to be dependent on the crystal surface orientation. No evidence of the activation of slip systems was discovered. The relative values of the contact pressure and Young’s modulus were in reasonable agreement with experiment and the coefficient of friction was found to be independent of the TiO2 polymorph. read less NOT USED (high confidence) S. Kerisit, N. Deskins, K. Rosso, and M. Dupuis, “A Shell Model for Atomistic Simulation of Charge Transfer in Titania,” Journal of Physical Chemistry C. 2008. link Times cited: 43 Abstract: The derivation of atomistic potential parameters, based on e… read moreAbstract: The derivation of atomistic potential parameters, based on electronic structure calculations, for modeling electron and hole polarons in titania polymorphs is presented. The potential model is a polarizable version of the Matsui and Akaogi model (Matsui, M.; Akaogi, M. Mol. Simul. 1991, 6, 239) that makes use of a shell model to account for the polarizability of oxygen ions. The −1 and +1 formal charges of the electron and hole polarons, respectively, are modeled by delocalizing the polaron’s charge over a titanium or oxygen ion, respectively, and its first nearest-neighbors. The charge distributions and the oxygen polarizability were fitted to the reorganization energies of a series of electron and hole polaron transfers in rutile and anatase obtained from electronic structure calculations at zero Kelvin and validated against lattice deformation due to both types of polaron. Good agreement was achieved for both properties. In addition, the potential model yields an accurate representation of a range of b... read less NOT USED (high confidence) Z. Wang and and G. Kroes, “Theoretical Study of Stable, Defect-Free (TiO2)n Nanoparticles with n = 10−16,” Journal of Physical Chemistry C. 2007. link Times cited: 112 Abstract: Novel defect-free (TiO2)n nanoparticles can be very useful f… read moreAbstract: Novel defect-free (TiO2)n nanoparticles can be very useful for mechanistic studies of photooxidation of water and organic pollutants on nanostructured oxide materials involving surface-trapped electrons and holes. In this study, the electronic structure and stability of (TiO2)n nanoparticles with n = 10−16 (∼1 nm in diameter) have been investigated using the density functional B3LYP/LANL2DZ method to find stable, TiO defect-free structures. The even-n (TiO2)n clusters tend to form compact (rather than linear or cyclic) covalent networks consisting of only 4-coordinated Ti(4) and 2-coordinated O(2) atoms, while odd-n clusters tend to form more ionic structures with additional highly coordinated Ti and O atoms. The new half-spherical (TiO2)15 15b cluster represents the smallest defect-free rutile nanocrystal. Strong vibrational bands around 770 and 820 cm-1 are found to be useful for identifying surface O(2) and O(3) species, respectively. Consistent with the odd−even oscillation of structural features of s... read less NOT USED (high confidence) V. V. Hoang, “The glass transition and diffusion in simulated liquid TiO2,” Journal of Physics: Condensed Matter. 2007. link Times cited: 5 Abstract: The glass transition and diffusion in liquid TiO2 have been … read moreAbstract: The glass transition and diffusion in liquid TiO2 have been studied in a model containing 3000 atoms via molecular dynamics (MD) simulation. The density dependence of the glass transition temperature, Tg, of liquid TiO2 has been found and is discussed. Diffusion of atomic species in 3.80 g cm−3 TiO2 models has been investigated over a wide temperature range from 2100 to 7000 K. We found that the temperature dependence of the diffusion constant of atomic species follows an Arrhenius law at relatively low temperatures above the melting point, and at higher temperatures it deviates from an Arrhenius law. Differences between the structures of amorphous TiO2 models at three different densities in the range from 3.80 to 4.20 g cm−3 have been found and are discussed. In addition, a transition from a low-density liquid (ldl) form to a high-density liquid (hdl) form was found and is discussed. read less NOT USED (high confidence) N. Huynh, V. V. Hoang, and H. Zung, “Structural properties of amorphous TiO2 nanoparticles,” The European Physical Journal D. 2007. link Times cited: 77 NOT USED (high confidence) N. Deskins, S. Kerisit, K. Rosso, and M. Dupuis, “Molecular Dynamics Characterization of Rutile-Anatase Interfaces,” Journal of Physical Chemistry C. 2007. link Times cited: 61 Abstract: We report molecular dynamics (MD) simulations of interfaces … read moreAbstract: We report molecular dynamics (MD) simulations of interfaces between rutile and anatase surfaces of TiO2. These interfaces are important for understanding mixed-phase catalysts, such as the Degussa P25 catalyst, and in particular as a first step toward characterizing electron/hole transport in these photoactive materials. Construction of these interfaces was possible with near-coincidence-site lattice (NCSL) theory. The results suggest adhesion energies for the most stable structures typically near −2 J/m2, and the interfaces appear energetically favorable due to an increase of six-coordinate Ti atoms (Ti6c). Two other notable observations emerge from this work. First, the interfaces are characterized as slightly disordered, with the disorder limited to a narrow region at the interface, in agreement with experiment. Second, formation of rutile octahedral structures was observed at the anatase side of the interface due to surface rearrangement. This appears as the beginning of an anatase-to-rutile phase tra... read less NOT USED (high confidence) V. Kopardé and P. Cummings, “Molecular Dynamics Study of Water Adsorption on TiO2 Nanoparticles,” Journal of Physical Chemistry C. 2007. link Times cited: 82 Abstract: This study uses molecular dynamics simulations performed in … read moreAbstract: This study uses molecular dynamics simulations performed in a parallel computing environment to investigate the adsorption of water molecules on the surface of anatase and rutile nanoparticles ranging from 2.5 to 4 nm at room temperature and at hydrothermal conditions. Phase enhancement occurs when these nanoparticles are immersed in water and the coverage per unit area of the nanoparticles increases with increase in size. The residence time of water molecules at the nanoparticle surface is ∼5−6 times longer at room temperature than that under hydrothermal conditions. Examining the oxygen and hydrogen atom distribution from the nanoparticle surfaces, it is found that there are two hydration layers around all the nanoparticles under consideration at all conditions. In the first hydration layer, water molecules have two different simultaneously existing orientational preferences depending on their local environment. read less NOT USED (high confidence) A. Skelton and T. Walsh, “Interaction of liquid water with the rutile TiO2 (110) surface,” Molecular Simulation. 2007. link Times cited: 27 Abstract: A force-field which describes the interaction between the Ti… read moreAbstract: A force-field which describes the interaction between the TiO2 (110) rutile surface and a modified TIP3P water [P. Mark and L. Nilsson, J. Phys. Chem. A, 105, 9954, (2001)] is tested against periodic density functional theory (PDFT). Optimizations of water on the non-hydroxylated and hydroxylated surfaces are performed using PDFT and the geometries are compared with optimizations of modified TIP3P water on the TiO2 surface using the force-field. The surface hydroxyl torsional profile is also compared using PDFT and force-field calculations as well as molecular dynamics (MD) simulations of the surface. MD simulations of liquid TIP3P water, containing dissolved Na+ and Cl− ions, on six TiO2 (110) surfaces at 298 K and 1 atm are performed for neutral surfaces and negatively-charged surfaces. Axial density and angular distributions show good agreement with results of Predota et al. [J. Phys. Chem. B, 108, 12049 (2004)] and X-ray crystal truncation rod experiments [Z. Zhang et al., Langmuir, 20, 4954 (2004)]. read less NOT USED (high confidence) V. V. Hoang, “Structural properties of simulated liquid and amorphous TiO2,” Physica Status Solidi B-basic Solid State Physics. 2007. link Times cited: 65 Abstract: Structural properties of liquid and amorphous TiO2 have been… read moreAbstract: Structural properties of liquid and amorphous TiO2 have been studied in a model containing 3000 particles under periodic boundary conditions with the pairwise interatomic potentials proposed by Matsui and Akaogi. Models have been obtained by cooling from the melt via molecular dynamics (MD) simulation. Structural properties of an amorphous model obtained at 350 K have been analyzed in details through the partial radial distribution functions (PRDFs), coordination number distributions, bond-angle distributions and interatomic distances. Calculations show that calculated data agree well with the experimental ones. The evolution of structure upon cooling from the melt was observed and discussed. Calculations show that amorphous TiO2 has a distorted octahedral network structure with the mean coordination number ZTi–O ≈ 6.0 and ZO–Ti ≈ 3.0. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) read less NOT USED (high confidence) S. Woodley, S. Hamad, J. A. Mejías, and C. Catlow, “Properties of small TiO2, ZrO2 and HfO2 nanoparticles,” Journal of Materials Chemistry. 2006. link Times cited: 60 Abstract: Ground state structures and energies are predicted for (MO2)… read moreAbstract: Ground state structures and energies are predicted for (MO2)n, where n = 1 to 8 and M is one of three isovalent cations, titanium(IV), zirconium(IV) and hafnium(IV), with the minimised binding energies calculated using Density Functional Theory. An increased number of single coordinated oxygen atoms, as opposed to more densely packed configurations, were found for the titania ground state clusters n = 5 and 7. We present, as a function of n, calculated nucleation energies, the energies of the respective highest occupied and lowest unoccupied molecular orbitals, harmonic frequencies of vibration and infrared spectra for all three compounds. Similarities and differences in the data produced for the three oxides are considered. Calculations were performed using the GAMESS-UK software on HPCx (phase 2a); aspects of the computational procedures are discussed. read less NOT USED (high confidence) S. Ogata et al., “Variable-charge interatomic potentials for molecular-dynamics simulations of TiO2,” Journal of Applied Physics. 1999. link Times cited: 60 Abstract: An interatomic potential model has been developed for molecu… read moreAbstract: An interatomic potential model has been developed for molecular-dynamics simulations of TiO2 (rutile) based on the formalism of Streitz and Mintmire [J. Adhes. Sci. Technol. 8, 853 (1994)], in which atomic charges vary dynamically according to the generalized electronegativity equalization principle. The present model potential reproduces the vibrational density of states, the pressure-dependent static dielectric constants, the melting temperature, and the surface relaxation of the rutile crystal, as well as the cohesive energy, the lattice constants, and the elastic moduli. We find the physical properties of rutile are significantly affected by dynamic charge transfer between Ti and O atoms. The potential allows us to perform atomistic simulations on nanostructured TiO2 with various kinds of interfaces (surfaces, grain boundaries, dislocations, etc.). read less NOT USED (high confidence) A. YazdanYar, U. Aschauer, and P. Bowen, “Interaction of biologically relevant ions and organic molecules with titanium oxide (rutile) surfaces: A review on molecular dynamics studies.,” Colloids and surfaces. B, Biointerfaces. 2018. link Times cited: 27 NOT USED (high confidence) D. Geohegan et al., “Laser Interactions for the Synthesis and In Situ Diagnostics of Nanomaterials.” 2014. link Times cited: 6 NOT USED (high confidence) D. V. Filyukov, E. Brodskaya, E. Piotrovskaya, and S. W. Leeuw, “Molecular-dynamics simulation of nanoclusters of crystal modifications of titanium dioxide,” Russian Journal of General Chemistry. 2007. link Times cited: 20 |