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.
206 Citations (135 used)
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USED (definite) F. Arca, J. P. Mendez, M. Ortiz, and P. Ariza, “Steric Interference in Bilayer Graphene with Point Dislocations,” Nanomaterials. 2019. link Times cited: 6 Abstract: We present evidence of strong steric interference in bilayer… read moreAbstract: We present evidence of strong steric interference in bilayer graphene containing offset point dislocations. Calculations are carried out with Large-scale Atomic/Molecular Massively Parallel Simulator (LAMMPS) using the Long-Range Carbon Bond-Order Potential (LCBOP) potential of Los et al.. We start by validating the potential in the harmonic response by comparing the predicted phonon dispersion curves to experimental data and other potentials. The requisite force constants are derived by linearization of the potential and are presented in full form. We then continue to validate the potential in applications involving the formation of dislocation dipoles and quadrupoles in monolayer configurations. Finally, we evaluate a number of dislocation quadrupole configurations in monolayer and bilayer graphene and document strong steric interactions due to out-of-plane displacements when the dislocations on the individual layers are sufficiently offset with respect to each other. read less USED (definite) A. C. Hansen-Dorr, L. Wilkens, A. Croy, A. Dianat, G. Cuniberti, and M. Kastner, “Combined molecular dynamics and phase-field modelling of crack propagation in defective graphene,” Computational Materials Science. 2019. link Times cited: 14 USED (definite) I. Lebedeva, A. Minkin, A. Popov, and A. Knizhnik, “Elastic constants of graphene: Comparison of empirical potentials and DFT calculations,” Physica E: Low-dimensional Systems and Nanostructures. 2019. link Times cited: 38 USED (definite) J. Xiao et al., “Dislocation behaviors in nanotwinned diamond,” Science Advances. 2018. link Times cited: 39 Abstract: The unprecedented hardness of nt-diamond originates from hig… read moreAbstract: The unprecedented hardness of nt-diamond originates from high lattice frictional stress and high athermal stress. Experimental results (Huang et al.) indicated that nanotwinned diamond (nt-diamond) has unprecedented hardness, whose physical mechanism has remained elusive. In this report, we categorize interaction modes between dislocations and twin planes in nt-diamond and calculate the associated reaction heat, activation energies, and barrier strength using molecular dynamics. On the basis of the Sachs model, twin thickness dependence of nt-diamond hardness is evaluated, which is in good agreement with the experimental data. We show that two factors contribute to the unusually high hardness of nt-diamond: high lattice frictional stress by the nature of carbon bonding in diamond and high athermal stress due to the Hall-Petch effect. Both factors stem from the low activation volumes and high activation energy for dislocation nucleation and propagation in diamond twin planes. This work provides new insights into hardening mechanisms in nt-diamond and will be helpful for developing new superhard materials in the future. read less USED (definite) C. Hofer et al., “Revealing the 3D structure of graphene defects,” 2D Materials. 2018. link Times cited: 19 Abstract: We demonstrate insights into the three-dimensional (3D) stru… read moreAbstract: We demonstrate insights into the three-dimensional (3D) structure of defects in graphene, in particular grain boundaries, obtained via a new approach using two transmission electron microscopy images recorded at different angles. The structure is revealed through an optimization process where both the atomic positions as well as the simulated imaging parameters are iteratively changed until the best possible match to the experimental images is found. We first demonstrate that this method works using an embedded defect in graphene that allows direct comparison to the computationally predicted 3D shape. We then apply the method to a set of grain boundary structures with misorientation angles spanning nearly the whole available range (2.6°–29.8°). The measured height variations at the boundaries reveal a strong correlation with the misorientation angle with lower angles resulting in stronger corrugation and larger kink angles. Our results allow for the first time a direct comparison to theoretical predictions for the corrugation at grain boundaries, revealing the measured kink angles are significantly smaller than the largest predicted ones. read less USED (definite) A. Sgouros, A. Sgouros, G. Kalosakas, G. Kalosakas, C. Galiotis, and K. Papagelis, “Uniaxial compression of suspended single and multilayer graphenes,” 2D Materials. 2016. link Times cited: 19 Abstract: The mechanical response of single and multiple graphene shee… read moreAbstract: The mechanical response of single and multiple graphene sheets under uniaxial compressive loads was studied with molecular dynamics (MD) simulations, using different semi-empirical force fields at different boundary conditions or constrains. Compressive stress–strain curves were obtained and the critical stress/strain values were derived. The MD results are compared to the linear elasticity continuum theory for loaded slabs. Concerning the length dependence of critical values, qualitatively similar behavior is observed between the theory and numerical simulations for single layer graphenes, as the critical stress/strain for buckling was found to scale to the inverse squared length. However discrepancies were noted for multilayer graphenes, where the critical buckling stress also decreased with increasing length, though at a slower rate than expected from elastic buckling analysis. read less USED (definite) M. V. Wijk and A. Fasolino, “Minimal graphene thickness for wear protection of diamond,” AIP Advances. 2014. link Times cited: 12 Abstract: We show, by means of molecular dynamics simulations, that th… read moreAbstract: We show, by means of molecular dynamics simulations, that the transformation from diamond to amorphous carbon occurring while sliding under pressure can be prevented by having at least two graphene layers between the diamond slabs. The resulting reduction of wear makes this combination of materials suitable for new coatings and micro- and nanoelectromechanical devices. Grain boundaries, vacancies and steps on the diamond surface do not change this prediction. We attribute this behavior to the bonding in layered materials like graphene. The strong in-plane bonding and the weak interlayer interaction that evolves to a strong interlayer repulsion under pressure prevent the transition to amorphous carbon when more than one layer is present. read less USED (definite) Y. He, H. Li, Y. Jiang, X.-Y. Li, and X. Bian, “Liquid-liquid phase transition and structure inheritance in carbon films,” Scientific Reports. 2014. link Times cited: 23 USED (definite) M. Bosson, S. Grudinin, X. Bouju, and S. Redon, “Interactive physically-based structural modeling of hydrocarbon systems,” J. Comput. Phys. 2012. link Times cited: 24 USED (definite) “Lattice Deformation, Low Energy Models and Flat Bands in Twisted Graphene Bilayers.,” arXiv: Strongly Correlated Electrons. 2019. link Times cited: 0 Abstract: Twisted graphene bilayers show a complex electronic structur… read moreAbstract: Twisted graphene bilayers show a complex electronic structure, further modified by interaction effects. The main features can be obtained from effective models, which make use a few phenomenological parameters. We analyze the influence of effects at the atomic scale, such as interlayer hopping and lattice relaxation, on the electronic bands. We assume that the twist angle and the size of the Moire pattern is fixed, as it is usually the case in experiments. We obtain a strong dependence of the electronic structure on details of the models at the atomic scale. We discuss how to incorporate this dependence on effective models read less USED (high confidence) A. Singh and Y. Li, “Reliable machine learning potentials based on artificial neural network for graphene,” ArXiv. 2023. link Times cited: 0 USED (high confidence) B. Karasulu, J.-M. Leyssale, P. Rowe, C. R. Weber, and C. de Tomas, “Accelerating the prediction of large carbon clusters via structure search: Evaluation of machine-learning and classical potentials,” Carbon. 2022. link Times cited: 11 USED (high confidence) A. Mescola et al., “Graphene Confers Ultralow Friction on Nanogear Cogs.,” Small. 2021. link Times cited: 13 Abstract: Friction-induced energy dissipation impedes the performance … read moreAbstract: Friction-induced energy dissipation impedes the performance of nanomechanical devices. Nevertheless, the application of graphene is known to modulate frictional dissipation by inducing local strain. This work reports on the nanomechanics of graphene conformed on different textured silicon surfaces that mimic the cogs of a nanoscale gear. The variation in the pitch lengths regulates the strain induced in capped graphene revealed by scanning probe techniques, Raman spectroscopy, and molecular dynamics simulation. The atomistic visualization elucidates asymmetric straining of CC bonds over the corrugated architecture resulting in distinct friction dissipation with respect to the groove axis. Experimental results are reported for strain-dependent solid lubrication which can be regulated by the corrugation and leads to ultralow frictional forces. The results are applicable for graphene covered corrugated structures with movable components such as nanoelectromechanical systems, nanoscale gears, and robotics. read less USED (high confidence) Z. Wu, X. Kuang, Z. Zhan, and S. Yuan, “Magic angle and plasmon mode engineering in twisted trilayer graphene with pressure,” Physical Review B. 2021. link Times cited: 5 Abstract: Recent experimental and theoretical investigations demonstra… read moreAbstract: Recent experimental and theoretical investigations demonstrate that twisted trilayer graphene (tTLG) is a highly tunable platform to study the correlated insulating states, ferromagnetism, and superconducting properties. Here we explore the possibility of tuning electronic correlations of the tTLG via a vertical pressure. A full tight-binding model is used to accurately describe the pressuredependent interlayer interactions. Our results show that pressure can push a relatively larger twist angle (for instance, 1.89◦) tTLG to reach the flat-band regime. Next, we obtain the relationship between the pressure-induced magic angle value and the critical pressure. These critical pressure values are almost half of that needed in the case of twisted bilayer graphene. Then, plasmonic properties are further investigated in the flat band tTLG with both zero-pressure magic angle and pressure-induced magic angle. Two plasmonic modes are detected in these two kinds of flat band samples. By comparison, one is a high energy damping-free plasmon mode that shows similar behavior, and the other is a low energy plasmon mode (flat-band plasmon) that shows obvious differences. The flat-band plasmon is contributed by both interband and intraband transitions of flat bands, and its divergence is due to the various shape of the flat bands in tTLG with zeropressure and pressure-induced magic angles. This may provide an efficient way of tuning between regimes with strong and weak electronic interactions in one sample and overcoming the technical requirement of precise control of the twist angle in the study of correlated physics. read less USED (high confidence) Z. Wu, Z. Zhan, and S. Yuan, “Lattice relaxation, mirror symmetry and magnetic field effects on ultraflat bands in twisted trilayer graphene,” Science China Physics, Mechanics & Astronomy. 2020. link Times cited: 22 USED (high confidence) J. Wang, D. Chen, T. Chen, and L. Shao, “Displacement of carbon atoms in few-layer graphene,” Journal of Applied Physics. 2020. link Times cited: 3 Abstract: Molecular dynamics simulations were performed to study the s… read moreAbstract: Molecular dynamics simulations were performed to study the susceptibility of carbon atom displacement under electron irradiation. The mapping of threshold displacement energies at different recoiling directions showed that the energies are very sensitive to the layer configurations and positions of neighboring atoms. Carbon atoms on the top and the bottom layers of few-layer graphene are most vulnerable to irradiation damage due to lack of constraints from the neighboring graphene layers. As indirect experiment evidence, transmission electron microscopy was performed on the edge of folded few-layer graphene, which made it possible to reveal “the inside” and compare irradiation tolerance of atoms at different layers, by using an electron analysis beam for both displacement creation and in situ characterization. read less USED (high confidence) F. Arca, J. P. Mendez, M. Ortiz, and M. P. Ariza, “Charge-carrier transmission across twins in graphene,” Journal of Physics: Condensed Matter. 2020. link Times cited: 3 Abstract: Twinning is a known accommodation mechanism of graphene that… read moreAbstract: Twinning is a known accommodation mechanism of graphene that results in low-energy microstructures or twins. In view of their mechanical stability, twins suggest themselves as a possible means of introducing extended defects in graphene leading to the opening of transmission band gaps. We investigate charge-carrier transmission across the twin structures in graphene using the Landauer–Büttiker (LB) formalism in combination with a tight-binding model. We verify the approach by means of selected comparisons with density functional theory (DFT) and non-equilibrium Green’s function (NEGF) calculations using the code SIESTA and TRANSIESTA. The calculations reveal that graphene twins open transport gaps depending on the twin geometry up to maximum of 1.15 eV. As previously reported for grain boundaries, we find that localized states arise at dislocation cores in the twin boundaries that introduce peaks near the Fermi level. read less USED (high confidence) M. Szendrő, P. Süle, G. Dobrik, and L. Tapasztó, “Ultra-flat twisted superlattices in 2D heterostructures,” npj Computational Materials. 2020. link Times cited: 2 USED (high confidence) M. Szendrő, A. P’alink’as, P. Süle, and Z. Osv’ath, “Anisotropic strain effects in small-twist-angle graphene on graphite,” Physical Review B. 2019. link Times cited: 6 Abstract: The direct experimental probing of locally varying lattice p… read moreAbstract: The direct experimental probing of locally varying lattice parameters and anisotropic lattice deformations in atomic multilayers is extremely challenging. Here, we develop a new combined numerical/graphical method for the analysis of irregular moire superstructures measured by scanning tunneling microscopy (STM) on a small-twist-angle ($\sim$0.6$^{\circ}$) graphene on highly oriented pyrolytic graphite (gr/HOPG). We observe distorted moire patterns with a spatially varying period in annealed gr/HOPG. The nanoscale modulation of the moire period observed by STM reflects a locally strained (and sheared) graphene with anisotropic variation of the lattice parameters. We use a specific algorithm based on a rigid lattice Fourier method, which is able to reconstruct the irregular and distorted moire patterns emerging from strain-induced lattice deformations. Our model is universal and can be used to study different moire patterns occurring in two-dimensional van der Waals heterostructures. Additionally, room temperature scanning tunneling spectroscopy measurements show electronic states at the Dirac point, localized on moire hills, which increase significantly the apparent corrugation of the moire pattern. The measured topography is compared to classical molecular dynamics simulations. Density functional theory (DFT) calculations confirm that an AAB stacked trilayer region itself can contribute electronic states near the Fermi-level, in agreement with the measured peak in the local density of states. Furthermore, CMD calculations reveal direction-dependent bond alternations ($\sim$0.5$\%$) around the stacking regions, induced by shear strain, which could influence electronic properties. read less USED (high confidence) A. Minkin, I. Lebedeva, A. Popov, and A. Knizhnik, “The Application of Empirical Potentials for Calculation of Elastic Properties of Graphene,” Technical Physics Letters. 2019. link Times cited: 3 USED (high confidence) U. Ludacka et al., “In situ control of graphene ripples and strain in the electron microscope,” npj 2D Materials and Applications. 2018. link Times cited: 18 USED (high confidence) A. Alsayoud et al., “Atomistic insights into the effect of polymerization on the thermophysical properties of 2-D C60 molecular solids,” Carbon. 2018. link Times cited: 7 USED (high confidence) P. Rowe, G. Csányi, D. Alfé, and A. Michaelides, “Development of a machine learning potential for graphene,” Physical Review B. 2017. link Times cited: 120 Abstract: © 2018 American Physical Society. We present an accurate int… read moreAbstract: © 2018 American Physical Society. We present an accurate interatomic potential for graphene, constructed using the Gaussian approximation potential (GAP) machine learning methodology. This GAP model obtains a faithful representation of a density functional theory (DFT) potential energy surface, facilitating highly accurate (approaching the accuracy of ab initio methods) molecular dynamics simulations. This is achieved at a computational cost which is orders of magnitude lower than that of comparable calculations which directly invoke electronic structure methods. We evaluate the accuracy of our machine learning model alongside that of a number of popular empirical and bond-order potentials, using both experimental and ab initio data as references. We find that whilst significant discrepancies exist between the empirical interatomic potentials and the reference data - and amongst the empirical potentials themselves - the machine learning model introduced here provides exemplary performance in all of the tested areas. The calculated properties include: graphene phonon dispersion curves at 0 K (which we predict with sub-meV accuracy), phonon spectra at finite temperature, in-plane thermal expansion up to 2500 K as compared to NPT ab initio molecular dynamics simulations and a comparison of the thermally induced dispersion of graphene Raman bands to experimental observations. We have made our potential freely available online at [http://www.libatoms.org]. read less USED (high confidence) C. Xu, C. Liu, and H. Wang, “Incipient plasticity of diamond during nanoindentation,” RSC Advances. 2017. link Times cited: 19 Abstract: Although diamond is the hardest material, it would still be … read moreAbstract: Although diamond is the hardest material, it would still be deformed by indenting. Therefore, investigating its incipient plasticity during the indenting process should be of great interest. Through molecular dynamics simulations, we have investigated the nanoindentations of diamond and probed its incipient plasticity according to the obtained load–displacement (P–h) curve. We found that the incipient plasticity of diamond should result from the propagation of the dislocations and the structural phase transitions from cubic diamond to lonsdaleite. The probable physical processes of incipient plasticity of diamond during nanoindentation were also suggested. The results presented in this work would not only provide clues for detecting the pop-in event of diamond in the future experimental work, but also offer new insights into the plasticity of diamond, which could be beneficial to the design of novel nano-structured superhard materials and elucidating the origins of wear and friction. read less USED (high confidence) Y. S. Al-Hamdani, D. Alfé, and A. Michaelides, “How strongly do hydrogen and water molecules stick to carbon nanomaterials,” Journal of Chemical Physics. 2017. link Times cited: 37 Abstract: The interaction strength of molecular hydrogen and water to … read moreAbstract: The interaction strength of molecular hydrogen and water to carbon nanomaterials is relevant to, among many applications, hydrogen storage, water treatment, and water flow. However, accurate interaction energies for hydrogen and water with carbon nanotubes (CNTs) remain scarce despite the importance of having reliable benchmark data to inform experiments and to validate computational models. Here, benchmark fixed-node diffusion Monte Carlo (DMC) interaction energies are provided for hydrogen and water monomers inside and outside a typical zigzag CNT. The DMC interaction energies provide valuable insight into molecular interactions with CNTs in general and are also expected to be particularly relevant to gas uptake studies on CNTs. In addition, a selection of density functional theory (DFT) exchange-correlation (xc) functionals and force field potentials that ought to be suitable for these systems is compared. An unexpected variation is found in the performance of DFT van der Waals (vdW) models in particul... read less USED (high confidence) P. Anees, M. C. Valsakumar, and B. Panigrahi, “Delineating the role of ripples on the thermal expansion of 2D honeycomb materials: graphene, 2D h-BN and monolayer (ML)-MoS2.,” Physical chemistry chemical physics : PCCP. 2016. link Times cited: 9 Abstract: We delineated the role of thermally excited ripples on the t… read moreAbstract: We delineated the role of thermally excited ripples on the thermal expansion properties of 2D honeycomb materials (free-standing graphene, 2D h-BN, and ML-MoS2), by explicitly carrying out three-dimensional (3D) and two-dimensional (2D) molecular dynamics simulations. In 3D simulations, the in-plane lattice parameter (a-lattice) of graphene and 2D h-BN shows thermal contraction over a wide range of temperatures and exhibits a strong system size dependence. The 2D simulations of the very same system show a reverse trend, where the a-lattice expands in the whole computed temperature range. In contrast to graphene and 2D h-BN, the a-lattice of ML-MoS2 shows thermal expansion in both 2D and 3D simulations and their system size dependence is marginal. By analyzing the phonon dispersion at 300 K, we found that the discrepancy between 2D and 3D simulations of graphene and 2D h-BN is due to the absence of out-of-plane bending modes (ZA) in 2D simulations, which is responsible for the thermal contraction of the a-lattice at low temperature. Meanwhile, all the phonon modes are present in the 2D phonon dispersion of ML-MoS2, which indicates that the origin of the ZA mode is not purely due to the out-of-plane movement of atoms and also its effect on thermal expansion is not significant as found in graphene and 2D h-BN. read less USED (high confidence) V. V. Hoang, L. T. C. Tuyen, and T. Q. Dong, “Stages of melting of graphene model in two-dimensional space,” Philosophical Magazine. 2016. link Times cited: 11 Abstract: Spontaneous melting of a perfect crystalline graphene model … read moreAbstract: Spontaneous melting of a perfect crystalline graphene model in 2D space is studied via molecular dynamics simulation. Model containing 104 atoms interacted via long-range bond-order potential (LCBOP) is heated up from 50 to 8,450 K in order to see evolution of various thermodynamic quantities, structural characteristics and occurrence of various structural defects. We find that spontaneous melting of our graphene model in 2D space exhibits a first-order behaviour of the transition from solid 2D graphene sheet into a ring-like structure 2D liquid. Occurrence and clustering of Stone–Wales defects are the first step of melting process followed by breaking of C–C bonds, occurrence/growth of various types of vacancies and multi-membered rings. Unlike that found for melting of a 2D crystal with an isotropic bonding, these defects do not occur homogeneously throughout the system, they have a tendency to aggregate into a region and liquid phase initiates/grows from this region via tearing-like or crack-propagation-like mechanism. Spontaneous melting point of our graphene model occurs at Tm = 7,750 K. The validity of classical nucleation theory and Berezinsky–Kosterlitz–Thouless–Nelson–Halperin–Young (BKTNHY) one for the spontaneous melting of our graphene model in strictly 2D space is discussed. read less USED (high confidence) R. Elder, M. Neupane, and T. Chantawansri, “Mechanical properties of homogeneous and heterogeneous layered 2D materials,” 2015 International Conference on Simulation of Semiconductor Processes and Devices (SISPAD). 2015. link Times cited: 0 Abstract: Transition metal dichalcogenides (TMDC) such as molybdenum d… read moreAbstract: Transition metal dichalcogenides (TMDC) such as molybdenum disulfide (MoS2) are 2D materials that are promising for flexible electronics and piezoelectric applications, but their low mechanical strength limits practical use. In this work, we study the mechanical properties of heterostructures containing MoS2 and graphene, another 2D material with exceptional mechanical properties, using atomistic molecular dynamics simulations of nanoindentation. We consider bi- and tri-layer heterostructures where graphene either supports or encapsulates MoS2, and we compare to the monolayers and homogeneous bilayers. We extract mechanical properties (Young's modulus) from nanoindentation simulations. All of the heterostructures have larger Young's moduli than the mono- and bi-layer MoS2, demonstrating that graphene provides mechanical reinforcement regardless of layer stacking order. Our results demonstrate the potential of heterostructures to improve the mechanical properties of TMDC materials, which would increase their utility for device applications. read less USED (high confidence) E. Koukaras, G. Kalosakas, C. Galiotis, and K. Papagelis, “Phonon properties of graphene derived from molecular dynamics simulations,” Scientific Reports. 2015. link Times cited: 103 USED (high confidence) L. Radosinski et al., “Photoinduced Conversion of Hybridization in Graphite,” Acta Physica Polonica A. 2012. link Times cited: 5 Abstract: Recent experiments indicate that a photostimulated graphite … read moreAbstract: Recent experiments indicate that a photostimulated graphite with a femtosecond laser pulse results in the formation of a stable domain with sp 3 like interlayer bonds. By means of the energy barrier minimization and molecular dynamics using the empirical Brenner potential we study a geometrical structure of the new phase. We clarify proliferation of the initial domain and prove that the overall process is a multiphoton one. Furthermore, we present a model describing the initial transformation — an interlayer charge transfer resulting in the localization of an exciton-like state. The local density approximation electronic structure analysis reveals that the electronic state of the new phase is an insulator immersed in semimetal. We study by means of the long-range carbon bond order potential the eect of the existence of the new phase on the surrounding graphite and propose a new mid step structure on the path of a photoinduced graphite‐diamond conversion. read less USED (low confidence) T. Jin, Z. Lin, B. Liu, J. Zheng, J. Chen, and A. Nie, “Unusual material removal characteristics of the novel graphite/diamond composite in mechanical polishing,” Tribology International. 2023. link Times cited: 1 USED (low confidence) L. Dai et al., “Mechanism of phase transition from OLCs with different structures to nPCD at high temperature and high pressure,” Journal of Materials Research and Technology. 2023. link Times cited: 0 USED (low confidence) J. Chen, W. Zhang, and K. Tong, “Effect of Twins on Scratching Behavior of Nanotwinned Diamond: A Molecular Dynamics Simulation,” SSRN Electronic Journal. 2023. link Times cited: 3 USED (low confidence) P. Ying, H. Dong, T. Liang, Z. Fan, Z. Zhong, and J. Zhang, “Atomistic insights into the mechanical anisotropy and fragility of monolayer fullerene networks using quantum mechanical calculations and machine-learning molecular dynamics simulations,” Extreme Mechanics Letters. 2022. link Times cited: 15 USED (low confidence) A. M. Barboza, L. C. R. Aliaga, D. Faria, and I. Bastos, “Bilayer Graphene Kirigami,” SSRN Electronic Journal. 2022. link Times cited: 1 USED (low confidence) L. Galiakhmetova, I. Pavlov, A. Bayazitov, I. Kosarev, and S. Dmitriev, “Mechanical Properties of Cubene Crystals,” Materials. 2022. link Times cited: 5 Abstract: The fullerene family, whose most popular members are the sph… read moreAbstract: The fullerene family, whose most popular members are the spherical C60 and C70 molecules, has recently added a new member, the cube-shaped carbon molecule C8 called a cubene. A molecular crystal based on fullerenes is called fullerite. In this work, based on relaxational molecular dynamics, two fullerites based on cubenes are described for the first time, one of which belongs to the cubic system, and the other to the triclinic system. Potential energy per atom, elastic constants, and mechanical stress components are calculated as functions of lattice strain. It has been established that the cubic cubene crystal is metastable, while the triclinic crystal is presumably the crystalline phase in the ground state (the potential energies per atom for these two structures are −0.0452 and −0.0480 eV, respectively).The cubic phase has a lower density than the monoclinic one (volumes per cubene are 101 and 97.7 Å3). The elastic constants for the monoclinic phase are approximately 4% higher than those for the cubic phase. The presented results are the first step in studying the physical and mechanical properties of C8 fullerite, which may have potential for hydrogen storage and other applications. In the future, the influence of temperature on the properties of cubenes will be analyzed. read less USED (low confidence) O. Bachurina, R. Murzaev, A. A. Kudreyko, S. Dmitriev, and D. Bachurin, “Atomistic study of two-dimensional discrete breathers in hcp titanium,” The European Physical Journal B. 2022. link Times cited: 2 USED (low confidence) G. G. Vidable, R. González, F. Valencia, N. Amigo, D. Tramontina, and E. Bringa, “Simulations of plasticity in diamond nanoparticles showing ultrahigh strength,” Diamond and Related Materials. 2022. link Times cited: 8 USED (low confidence) Q. Bai, H. Wang, Y. Dou, W. Guo, and S. Chen, “Molecular dynamics simulation for plastic deformation mechanisms of single crystal diamond during nanoindentation,” Molecular Simulation. 2022. link Times cited: 1 Abstract: ABSTRACT The elastic-plastic deformation mechanism of single… read moreAbstract: ABSTRACT The elastic-plastic deformation mechanism of single crystal diamond under spherical nanoindentation was emphasised using molecular dynamics (MD). The benchmark tests to determine the empirical potential that accurately describe the interactions between diamond atoms were completed. Tensile strength of diamond at different temperatures was studied under the empirical potential preferentially selected by benchmark tests. The nanoindentation process of the diamond is subsequently carried out on the surface (001). Plastic deformation behaviour of brittle diamond was found, such as amorphisation, phase transformation, graphitisation and dislocation evolution were analysed and discussed using combined methods. The simulation results show that the plastic deformation behaviour of the diamond material is also evident, even though diamond is a brittle material with high strength and hardness. ‘Pop-in’ event of the P-h curve is the turning point from elastic to plastic deformation. The elastic stage can be divided into the pure elastic and the quasi-elastic deformation stages. The plastic deformation behaviour of diamond is dominated by a combination of phase transformation, graphitisation and dislocation nucleation. It is also found that the primary dislocation type is 1/2<110> perfect dislocation, which was distributed in the area of large stress concentration below the indenter. read less USED (low confidence) Z. Mei, R. Ponciroli, and A. Petersen, “Wigner energy in irradiated graphite: a first-principles study,” Journal of Nuclear Materials. 2022. link Times cited: 2 USED (low confidence) R. Ponciroli, P. Shriwise, Z. Mei, N. Stauff, A. Petersen, and P. Romano, “Simulation-based methodology to assess the lattice defects creation as energy storing process,” Annals of Nuclear Energy. 2022. link Times cited: 3 USED (low confidence) M. Konnik, F. Panerai, and K. Stephani, “The role of impurities and degradation on the thermal conductivity of carbon fiber and amorphous carbon,” Carbon Trends. 2022. link Times cited: 1 USED (low confidence) U. Tewary et al., “The Origin of Graphite Morphology in Cast Iron,” Acta Materialia. 2022. link Times cited: 13 USED (low confidence) R. Ponciroli et al., “Integration of a Wigner effect-based energy storage system with an advanced nuclear reactor,” Nuclear Engineering and Design. 2021. link Times cited: 3 USED (low confidence) D. Luo et al., “Atomistic Evidence of Nucleation Mechanism for the Direct Graphite-to-Diamond Transformation.” 2021. link Times cited: 1 Abstract:
The direct graphite-to-diamond transformation mechanism ha… read moreAbstract:
The direct graphite-to-diamond transformation mechanism has been a subject of intense study and remains debated concerning the initial stages of the conversion, the intermediate phases, and their transformation pathways. Here, we successfully recover samples at early conversion stage by tuning high-pressure/high-temperature conditions and reveal direct evidence supporting the nucleation-growth mechanism. Atomistic observations show that intermediate orthorhombic graphite phase mediates the growth of diamond nuclei. Furthermore, we observe that quenchable orthorhombic and rhombohedra graphite are stabilized in buckled graphite at lower temperatures. These intermediate phases are further converted into hexagonal and cubic diamond at higher temperatures following energetically favorable pathways in the order: graphite -> orthorhombic graphite -> hexagonal diamond, graphite -> orthorhombic graphite -> cubic diamond, graphite -> rhombohedra graphite -> cubic diamond. These results significantly improve our understanding of the transformation mechanism, enabling the synthesis of different high-quality forms of diamond from graphite. read less USED (low confidence) Y. Xie, K. Shibata, and T. Mizoguchi, “Integrated structural reconstruction of unit structures of the meta-stable grain boundaries in diamond-structured materials presents first-order like phase transition.” 2021. link Times cited: 0 Abstract:
One of the important issues of studying grain boundaries (… read moreAbstract:
One of the important issues of studying grain boundaries (GBs) which has recently attracted increasing interests is to investigate the phase behavior of GBs that one GB with determined disorientation and plane orientation (known as macroscopic parameters) can exist as distinct phases and perform phase transition. While such an issue has been investigated in fcc and bcc metals, GB phases in other elemental materials have not been reported. This work by applying molecular dynamics (MD) simulation explored totally around 7000 meta-stable GB phases of the <110>∑9(22‾1‾) symmetric tilt GB of silicon, germanium and diamond carbon as diamond-structured elemental materials. Meta-stable phases commonly exist in different elements were discovered and some of them were successfully verified to be reasonable by first-principle simulation. The verified meta-stable GBs were subsequently proved to have different capability to transform to the ground-stable GB at elevated temperature under MD simulation and to perform different pre-melting behaviors. We discovered a bi-directional structural reconstruction mechanism of the unit structure belonging to one of the verified meta-stable phases, by which the unit structures can transform to identical unit structures of the ground-stable GB which can present ‘opposite orientation’. Through computing the kinetic barriers by nudged-elastic-band and annealing simulation using MD, the integral behavior of the unit structures’ reconstruction is found to be a first-order like phase transition. Our work extended the research on GB phases from metals to diamond-structured materials and discovered a new GB phase transition mechanism which has not been reported before. read less USED (low confidence) G. Dobrik et al., “Large-area nanoengineering of graphene corrugations for visible-frequency graphene plasmons,” Nature Nanotechnology. 2021. link Times cited: 16 USED (low confidence) Y. Pan et al., “Extreme mechanical anisotropy in diamond with preferentially oriented nanotwin bundles,” Proceedings of the National Academy of Sciences. 2021. link Times cited: 7 Abstract: Significance Diamond is an essential material for industrial… read moreAbstract: Significance Diamond is an essential material for industrial and scientific applications due to its exceptional properties. The regulation of diamond performance through microstructural design is a challenging and hot topic. Here, we report the synthesis of diamond with preferentially oriented nanotwin bundles via direct phase transformation of superaligned multiwalled carbon nanotube films under high temperature and pressure. The preferentially oriented nanotwin bundles endow diamond with the highest hardness anisotropy ever recorded and a record hardness value in the direction perpendicular to the oriented nanotwin bundles. Current findings provide valuable insights on the microstructural design and modification of diamond and related materials, contributing to the further tuning of properties in the future. Mechanical properties of covalent materials can be greatly enhanced with strategy of nanostructuring. For example, the nanotwinned diamond with an isotropic microstructure of interweaved nanotwins and interlocked nanograins shows unprecedented isotropic mechanical properties. How the anisotropic microstructure would impact on the mechanical properties of diamond has not been fully investigated. Here, we report the synthesis of diamond from superaligned multiwalled carbon nanotube films under high pressure and high temperature. Structural characterization reveals preferentially oriented diamond nanotwin bundles with an average twin thickness of ca. 2.9 nm, inherited from the directional nanotubes. This diamond exhibits extreme mechanical anisotropy correlated with its microstructure (e.g., the average Knoop hardness values measured with the major axis of the indenter perpendicular and parallel to nanotwin bundles are 233 ± 8 and 129 ± 9 GPa, respectively). Molecular dynamics simulation reveals that, in the direction perpendicular to the nanotwin bundles, the dense twin boundaries significantly hinder the motion of dislocations under indentation, while such a resistance is much weaker in the direction along the nanotwin bundles. Current work verifies the hardening effect in diamond via nanostructuring. In addition, the mechanical properties can be further tuned (anisotropy) with microstructure design and modification. read less USED (low confidence) M. Braun, F. Arca, and M. P. Ariza, “Computational assessment of Stone-Wales defects on the elastic modulus and vibration response of graphene sheets,” International Journal of Mechanical Sciences. 2021. link Times cited: 4 USED (low confidence) I. E. Golentus, “Long-range in-plane elastic displacement fields of double vacancies in graphene,” Physica E: Low-dimensional Systems and Nanostructures. 2021. link Times cited: 0 USED (low confidence) J. G. Mchugh, P. Mouratidis, A. Impellizzeri, K. Jolley, D. Erbahar, and C. Ewels, “Prismatic Edge Dislocations in Graphite,” MatSciRN EM Feeds. 2021. link Times cited: 9 Abstract: Dislocations are a central concept in materials science, whi… read moreAbstract: Dislocations are a central concept in materials science, which dictate the plastic deformation and damage evolution in materials. Layered materials such as graphite admit two general types of interlayer dislocations: basal and prismatic dislocations, of which prismatic dislocations have been relatively less studied. Using density functional theory (DFT) calculations, we have examined different prismatic core structures in graphite and evaluated their structure, energetics and mobility. We find close energetic interplay between bonded and “free-standing” core structures in both zigzag and armchair directions, with a reconstructed stable zigzag core identified. We explore grain boundaries and prismatic dislocation pile-up, identifying metastable structures which may be important in energy storage. The role of interlayer stacking in core structure, dislocation glide and climb is also considered in-depth. Our calculations suggest that the prismatic dislocation core is stable up to high temperatures of approximately 1500K in bulk graphite. Above this temperature, the breaking of bonds in the dislocation core can facilitate climb, grain-boundary motion, and the annealing of damage through prismatic dislocation glide. read less USED (low confidence) B. Goh and J. Choi, “Mechanical evaluation of bidirectional surface deformation in contact between nanometer-sized carbon particle and copper substrate: A molecular dynamics approach,” Surfaces and Interfaces. 2021. link Times cited: 3 USED (low confidence) F. Thiemann, P. Rowe, A. Zen, E. A. Müller, and A. Michaelides, “Defect-Dependent Corrugation in Graphene.,” Nano letters. 2021. link Times cited: 20 Abstract: Graphene's intrinsically corrugated and wrinkled topolo… read moreAbstract: Graphene's intrinsically corrugated and wrinkled topology fundamentally influences its electronic, mechanical, and chemical properties. Experimental techniques allow the manipulation of pristine graphene and the controlled production of defects which allows one to control the atomic out-of-plane fluctuations and thus tune graphene's properties. Here, we perform large scale machine learning-driven molecular dynamics simulations to understand the impact of defects on the structure of graphene. We find that defects cause significantly higher corrugation leading to a strongly wrinkled surface. The magnitude of this structural transformation strongly depends on the defect concentration and specific type of defect. Analyzing the atomic neighborhood of the defects reveals that the extent of these morphological changes depends on the preferred geometrical orientation and the interactions between defects. While our work highlights that defects can strongly affect graphene's morphology, it also emphasizes the differences between distinct types by linking the global structure to the local environment of the defects. read less USED (low confidence) G. Manolis, P. Dineva, T. Rangelov, and D. Sfyris, “Mechanical models and numerical simulations in nanomechanics: A review across the scales,” Engineering Analysis with Boundary Elements. 2021. link Times cited: 17 USED (low confidence) P. Chrostoski, C. Silva, and P. Fraundorf, “The rates of unlayered graphene formation in a supercooled carbon melt at low pressure,” MRS Advances. 2021. link Times cited: 1 Abstract: Elemental carbon has important structural diversity, ranging… read moreAbstract: Elemental carbon has important structural diversity, ranging from nanotubes to graphite and diamond. Studies of primitive meteorite extracted micron-size core/rim carbon spheres suggest they formed via the solidification of condensed carbon vapor droplets, followed by gas-to-solid carbon coating to form the graphite rims. We show here how analytical models of reaction limited nucleation and growth can be used to connect thermal history (e.g., time at temperature) to electron microscope observations of mean graphene sheet size and number density. Atomistic models using the LCBOP semi-empirical potential show promise for estimating latent heat and the temperature dependence of barrier heights, which are not yet incorporated in the model. We also show that growth of 2D clusters from a 2D liquid takes place more rapidly than from a 3D liquid, which with suitable scaling might open the door to simulating growth over millisecond time scales in the study of liquid carbon’s solidification at low pressures. read less USED (low confidence) M. J. Tolladay, F. Scarpa, and N. Allan, “Interatomic forces breaking carbon-carbon bonds,” Carbon. 2021. link Times cited: 5 USED (low confidence) I. Syuhada, N. Hauwali, A. Rosikhin, E. Sustini, F. A. Noor, and T. Winata, “Bond order redefinition needed to reduce inherent noise in molecular dynamics simulations,” Scientific Reports. 2021. link Times cited: 1 USED (low confidence) Z. Liu, B. Lin, X. Liang, and A. Du, “Study on the effect of laser-assisted machining on tool wear based on molecular dynamics simulation,” Diamond and Related Materials. 2020. link Times cited: 15 USED (low confidence) Q. Liu, L. Li, Y. Jeng, G. Zhang, C. Shuai, and X. Zhu, “Effect of interatomic potentials on modeling the nanostructure of amorphous carbon by liquid quenching method,” Computational Materials Science. 2020. link Times cited: 9 USED (low confidence) S. Paul, K. Momeni, and V. Levitas, “Shear-induced diamondization of multilayer graphene structures: A computational study,” Carbon. 2020. link Times cited: 17 USED (low confidence) N. Orekhov, G. Ostroumova, and V. Stegailov, “High temperature pure carbon nanoparticle formation: Validation of AIREBO and ReaxFF reactive molecular dynamics,” Carbon. 2020. link Times cited: 40 USED (low confidence) J. Xiao, B. Wen, B. Xu, X. Zhang, Y. Wang, and Y. Tian, “Intersectional nanotwinned diamond-the hardest polycrystalline diamond by design,” npj Computational Materials. 2020. link Times cited: 23 USED (low confidence) M. Katsnelson, “The Physics of Graphene.” 2020. link Times cited: 38 Abstract: Leading graphene research theorist Mikhail I. Katsnelson sys… read moreAbstract: Leading graphene research theorist Mikhail I. Katsnelson systematically presents the basic concepts of graphene physics in this fully revised second edition. The author illustrates and explains basic concepts such as Berry phase, scaling, Zitterbewegung, Kubo, Landauer and Mori formalisms in quantum kinetics, chirality, plasmons, commensurate-incommensurate transitions and many others. Open issues and unsolved problems introduce the reader to the latest developments in the field. New achievements and topics presented include the basic concepts of Van der Waals heterostructures, many-body physics of graphene, electronic optics of Dirac electrons, hydrodynamics of electron liquid and the mechanical properties of one atom-thick membranes. Building on an undergraduate-level knowledge of quantum and statistical physics and solid-state theory, this is an important graduate textbook for students in nanoscience, nanotechnology and condensed matter. For physicists and material scientists working in related areas, this is an excellent introduction to the fast-growing field of graphene science. read less USED (low confidence) S. Srinivasan et al., “Machine learning the metastable phase diagram of covalently bonded carbon,” Nature Communications. 2020. link Times cited: 7 USED (low confidence) C. Androulidakis, E. Koukaras, G. Paterakis, G. Trakakis, and C. Galiotis, “Tunable macroscale structural superlubricity in two-layer graphene via strain engineering,” Nature Communications. 2020. link Times cited: 71 USED (low confidence) M. Katsnelson, “Optics and response functions,” The Physics of Graphene. 2020. link Times cited: 2 USED (low confidence) M. Katsnelson, “Scattering mechanisms and transport properties,” The Physics of Graphene. 2020. link Times cited: 0 USED (low confidence) M. Katsnelson, “Quantum transport via evanescent waves,” The Physics of Graphene. 2020. link Times cited: 0 USED (low confidence) F. Arca, J. P. Mendez, M. Ortiz, and M. P. Ariza, “Spontaneous twinning as an accommodation mechanism in monolayer graphene,” European Journal of Mechanics A-solids. 2020. link Times cited: 4 USED (low confidence) M. Katsnelson, “Many-body effects in graphene.” 2020. link Times cited: 0 USED (low confidence) M. Katsnelson, “The Klein paradox and chiral tunneling.” 2020. link Times cited: 0 USED (low confidence) M. Katsnelson, “Twisted bilayer graphene.” 2020. link Times cited: 79 USED (low confidence) M. Katsnelson, “The Coulomb problem.” 2020. link Times cited: 0 USED (low confidence) M. Katsnelson, “Spin effects and magnetism.” 2020. link Times cited: 0 USED (low confidence) J. Seebeck, P. Schiffels, S. Schweizer, J.-R. Hill, and R. Meißner, “Electrical Double Layer Capacitance of Curved Graphite Electrodes,” The Journal of Physical Chemistry C. 2020. link Times cited: 9 Abstract: To improve the understanding of the relation between electro… read moreAbstract: To improve the understanding of the relation between electrode curvature and energy storage mechanisms, a systematic investigation of the correlation between convex and concave electrode surfaces a... read less USED (low confidence) Z. Zhang and Z. Hossain, “Geometric confinement governs toughness and strength in defective diamond nanowires,” Physical Review B. 2020. link Times cited: 1 USED (low confidence) S. Thomas, S. Jana, B. Jun, C. Lee, and S. U. Lee, “Temperature-dependent lithium diffusion in phographene: Insights from molecular dynamics simulation,” Journal of Industrial and Engineering Chemistry. 2020. link Times cited: 7 USED (low confidence) J. Hernández-Muñoz, P. Tarazona, R. Ramírez, C. Herrero, and E. Chacón, “Structure factor of fluctuating interfaces: From liquid surfaces to suspended graphene,” Physical Review B. 2019. link Times cited: 2 Abstract: We obtain the density-density correlation structure in molec… read moreAbstract: We obtain the density-density correlation structure in molecular dynamics (MD) simulations of graphene, and analyze it within the capillary wave theory (CWT), developed for fluid surfaces, to describe the thermal corrugations of the graphene sheet with a wave-vector-dependent surface tension $\ensuremath{\gamma}({q}_{x})$. The density correlation function (from the atomic positions) is compared with the theoretical prediction by Bedeaux and Weeks (BW), within the CWT, in terms of $\ensuremath{\gamma}({q}_{x})$ and the density profile. The agreement is very good, even for relatively large ${q}_{x}\ensuremath{\approx}0.2{\AA{}}^{\ensuremath{-}1}$, and with very little role for the correlation background, which sets an important difficulty for liquid surfaces. We present and test a generic prediction for the structure factor $S({q}_{x},{q}_{z})$ from $\ensuremath{\gamma}({q}_{x})$, that contains and goes beyond the classical asymptotic expression, developed by Sinha, for the analysis of x-ray surface scattering. We compare our prediction with the formula used in the interpretation of experimental data, that assumes a direct relationship between $\ensuremath{\gamma}({q}_{x})$ and the correlation structure for the same wave vector ${q}_{x}$. That relation is exact only for the first (Wertheim's) term of the BW series, and we use our results to test the accuracy of the function $\ensuremath{\gamma}({q}_{x})$ estimated through that method. read less USED (low confidence) J. Li, S. Gao, R. Long, W. Liu, and Z. Liu, “Self-pumped evaporation for ultra-fast water desalination and power generation,” Nano Energy. 2019. link Times cited: 17 USED (low confidence) X. Li, H. Mizuseki, S. J. Pai, and K.-R. Lee, “Reactive molecular dynamics simulation of the amorphous carbon growth: Effect of the carbon triple bonds,” Computational Materials Science. 2019. link Times cited: 5 USED (low confidence) A. Mohammed, H. Sehitoglu, and R. Rateick, “Interface graphitization of carbon-carbon composites by nanoindentation,” Carbon. 2019. link Times cited: 15 USED (low confidence) K. Skrobas, S. Stelmakh, S. Gierlotka, and B. Palosz, “A model of density waves in atomic structure of nanodiamond by molecular dynamics simulations,” Diamond and Related Materials. 2019. link Times cited: 10 USED (low confidence) C. Xu, G. He, C. Liu, and H. Wang, “Twin-size effects on the hardness and plastic deformation mechanisms of nanotwinned diamond,” Ceramics International. 2018. link Times cited: 18 USED (low confidence) S. Thomas, E. B. Nam, and S. U. Lee, “Atomistic Dynamics Investigation of the Thermomechanical Properties and Li Diffusion Kinetics in ψ-Graphene for LIB Anode Material.,” ACS applied materials & interfaces. 2018. link Times cited: 31 Abstract: A fundamental understanding of the thermomechanical properti… read moreAbstract: A fundamental understanding of the thermomechanical properties of electrode materials and Li-ion diffusion kinetics is indispensable for designing high-performance Li-ion batteries (LIBs) with high structural stability and safety. Herein, we performed both molecular dynamics (MD) simulations and density functional theory (DFT) calculations to investigate the thermomechanical properties and Li diffusion kinetics in a two-dimensional (2D) defect-filled graphene-like membrane consisting of 5-, 6-, and 7-membered rings, called psi (ψ)-graphene. Our results reveal that ψ-graphene has a negative linear thermal expansion coefficient, a high specific heat capacity, and high elastic constants that satisfy the Born's criterion for mechanical stability, which can be elucidated as the evidence of strong anharmonicity in ψ-graphene because of the soft out-of-plane bending modes. These characteristics can help prevent the thermal runaway that can occur during overheating and prevent structural damage because of the severe volume expansion of the LIBs. In addition, the Li diffusion coefficient was estimated to be 10-9 cm2/s at 300 K with a low Li migration activation energy (<0.16 eV), which suggests favorable electrode kinetics with fast Li conduction. Our DFT calculations also show that ψ-graphene can possess a fairly good theoretical capacity (339 mA h g-1) and a lower Li diffusion barrier (<0.21 eV). Our results suggest that the new fundamental insights presented here will help to stimulate further experimental work on ψ-graphene for promising future applications as a superior electrode material for LIBs. read less USED (low confidence) H. Yang et al., “Homogeneous and heterogeneous dislocation nucleation in diamond,” Diamond and Related Materials. 2018. link Times cited: 8 USED (low confidence) M. Wen, S. Carr, S. Fang, E. Kaxiras, and E. Tadmor, “Dihedral-angle-corrected registry-dependent interlayer potential for multilayer graphene structures,” Physical Review B. 2018. link Times cited: 39 Abstract: The structural relaxation of multilayer graphene is essentia… read moreAbstract: The structural relaxation of multilayer graphene is essential in describing the interesting electronic properties induced by intentional misalignment of successive layers, including the recently reported superconductivity in twisted bilayer graphene. This is difficult to accomplish without an accurate interatomic potential. Here, we present a new, registry-dependent Kolmogorov-Crespi type interatomic potential to model interlayer interactions in multilayer graphene structures. It consists of two parts representing attractive interaction due to dispersion, and repulsive interaction due to anisotropic overlap of electronic orbitals. An important new feature is a dihedral-angle-dependent term that is added to the repulsive part in order to describe correctly several distinct stacking states that the original Kolmogorov-Crespi potential cannot distinguish. We refer to the new model as the Dihedral-angle-corrected Registry-dependent Interlayer Potential (DRIP). Computations for several test problems show that DRIP correctly reproduces the binding, sliding, and twisting energies and forces obtained from ab initio total-energy calculations based on density functional theory. We use the new potential to study the structural properties of a twisted graphene bilayer and the exfoliation of graphene from graphite. Our potential is available through the OpenKIM interatomic potential repository at https://openkim.org. read less USED (low confidence) A. Chartier, L. Brutzel, and J. Pageot, “Irradiation damage in nuclear graphite at the atomic scale,” Carbon. 2018. link Times cited: 21 USED (low confidence) A. Sgouros, G. Kalosakas, G. Kalosakas, K. Papagelis, and C. Galiotis, “Compressive response and buckling of graphene nanoribbons,” Scientific Reports. 2018. link Times cited: 22 USED (low confidence) I. Maity, P. Maiti, and M. Jain, “Temperature Dependent Layer Breathing Modes in Two Dimensional Materials,” Physical Review B. 2018. link Times cited: 7 Abstract: Relative out-of-plane displacements of the constituent layer… read moreAbstract: Relative out-of-plane displacements of the constituent layers of two-dimensional materials give rise to unique low-frequency breathing modes. By computing the height-height correlation functions from molecular dynamics simulations, we show that the layer breathing modes (LBMs) can be mapped consistently to vibrations of a simple linear chain model. Our calculated thickness dependence of LBM frequencies for few-layer (FL) graphene and molybdenum disulfide $({\mathrm{MoS}}_{2})$ are in excellent agreement with available experiments. Our results show a redshift of LBM frequency with an increase in temperature, which is a direct consequence of anharmonicities present in the interlayer interaction. We also predict the thickness and temperature dependence of LBM frequencies for FL hexagonal boron nitride. Our Rapid Communication provides a simple and efficient way to probe the interlayer interaction for layered materials and their heterostructures with the inclusion of anharmonic effects. read less USED (low confidence) F. Xu, F. Fang, and X. Zhang, “Hard particle effect on surface generation in nano-cutting,” Applied Surface Science. 2017. link Times cited: 34 USED (low confidence) Z. Fthenakis, G. Kalosakas, G. D. Chatzidakis, C. Galiotis, K. Papagelis, and N. Lathiotakis, “Atomistic potential for graphene and other sp2 carbon systems.,” Physical chemistry chemical physics : PCCP. 2017. link Times cited: 9 Abstract: We introduce a torsional force field for sp2 carbon to augme… read moreAbstract: We introduce a torsional force field for sp2 carbon to augment an in-plane atomistic potential of a previous work [G. Kalosakas et al., J. Appl. Phys., 2013, 113, 134307] so that it is applicable to out-of-plane deformations of graphene and related carbon materials. The introduced force field is fit to reproduce density-functional-theory calculation data of appropriately chosen structures. The aim is to create a force field that is as simple as possible so it can be efficient for large scale atomistic simulations of various sp2 carbon structures without significant loss of accuracy. We show that the complete proposed potential reproduces characteristic properties of fullerenes and carbon nanotubes. In addition, it reproduces very accurately the out-of-plane acoustic and optical modes of graphene's phonon dispersion as well as all phonons with frequencies up to 1000 cm-1. read less USED (low confidence) M. Katsnelson and A. Fasolino, “Graphene: Basic Properties.” 2017. link Times cited: 2 USED (low confidence) R. Guerra, M. V. van Wijk, A. Vanossi, A. Fasolino, and E. Tosatti, “Graphene on h-BN: to align or not to align?,” Nanoscale. 2017. link Times cited: 14 Abstract: The contact strength, adhesion and friction, between graphen… read moreAbstract: The contact strength, adhesion and friction, between graphene and an incommensurate crystalline substrate such as h-BN depends on their relative alignment angle θ. The well-established Novaco-McTague (NM) theory predicts for a monolayer graphene on a hard bulk h-BN crystal face a small spontaneous misalignment, here θNM ≃ 0.45 degrees which if realized would be relevant to a host of electronic properties besides the mechanical ones. Because experimental equilibrium is hard to achieve, we inquire theoretically about alignment or misalignment by simulations based on dependable state-of-the-art interatomic force fields. Surprisingly at first, we find compelling evidence for θ = 0, i.e., full energy-driven alignment in the equilibrium state of graphene on h-BN. Two factors drive this deviation from the NM theory. First, graphene is not flat, developing on h-BN a long-wavelength out-of-plane corrugation. Second, h-BN is not hard, releasing its contact stress by planar contractions/expansions that accompany the interface moiré structure. Repeated simulations by artificially forcing graphene to keep flat, and h-BN to keep rigid, indeed yield an equilibrium misalignment similar to θNM as expected. Subsequent sliding simulations show that friction of graphene on h-BN, small and essentially independent of misalignments in the artificial frozen state, strongly increases in the more realistic corrugated, strain-modulated, aligned state. read less USED (low confidence) R. Murzaev, D. Bachurin, E. Korznikova, and S. Dmitriev, “Localized vibrational modes in diamond,” Physics Letters A. 2017. link Times cited: 47 USED (low confidence) F. Lin, Y. Xiang, and H. S. Shen, “Temperature dependent mechanical properties of graphene reinforced polymer nanocomposites – A molecular dynamics simulation,” Composites Part B-engineering. 2017. link Times cited: 234 USED (low confidence) G. Argentero et al., “Unraveling the 3D Atomic Structure of a Suspended Graphene/hBN van der Waals Heterostructure,” Nano Letters. 2017. link Times cited: 79 Abstract: In this work we demonstrate that a free-standing van der Waa… read moreAbstract: In this work we demonstrate that a free-standing van der Waals heterostructure, usually regarded as a flat object, can exhibit an intrinsic buckled atomic structure resulting from the interaction between two layers with a small lattice mismatch. We studied a freely suspended membrane of well-aligned graphene on a hexagonal boron nitride (hBN) monolayer by transmission electron microscopy (TEM) and scanning TEM (STEM). We developed a detection method in the STEM that is capable of recording the direction of the scattered electron beam and that is extremely sensitive to the local stacking of atoms. A comparison between experimental data and simulated models shows that the heterostructure effectively bends in the out-of-plane direction, producing an undulated structure having a periodicity that matches the moiré wavelength. We attribute this rippling to the interlayer interaction and also show how this affects the intralayer strain in each layer. read less USED (low confidence) H. N. Pishkenari and P. G. Ghanbari, “Vibrational properties of C60: A comparison among different inter-atomic potentials,” Computational Materials Science. 2016. link Times cited: 11 USED (low confidence) C. Androulidakis, E. Koukaras, J. Parthenios, G. Kalosakas, K. Papagelis, and C. Galiotis, “Graphene flakes under controlled biaxial deformation,” Scientific Reports. 2015. link Times cited: 80 USED (low confidence) N. Orekhov and V. Stegailov, “Molecular-dynamics based insights into the problem of graphite melting,” Journal of Physics: Conference Series. 2015. link Times cited: 11 Abstract: The experimental data on graphite melting temperature remain… read moreAbstract: The experimental data on graphite melting temperature remain poorly determined despite the long history of investigations. The experimental results cover the wide span from 3800 to 5000 K that is an essentially larger uncertainty than the errors of individual experiments. In this work, we deploy the molecular dynamics method and expand our previous study of the kinetics of graphite melting comparing different carbon interatomic potentials. Here we consider the melting front propagation rate, the aspects of defect formation and single graphene layer decay. The results obtained allow us also to discuss the aspects of graphite-vapor and possible graphite-carbyne phase transitions at low pressures. read less USED (low confidence) A. Chartier, L. Brutzel, B. Pannier, and P. Baranek, “Atomic scale mechanisms for the amorphisation of irradiated graphite,” Carbon. 2015. link Times cited: 24 USED (low confidence) P. Anees, M. C. Valsakumar, and B. Panigrahi, “Temperature dependent phonon frequency shift and structural stability of free-standing graphene: a spectral energy density analysis,” 2D Materials. 2015. link Times cited: 17 Abstract: A spectral energy density based formalism is implemented to … read moreAbstract: A spectral energy density based formalism is implemented to probe the temperature dependent frequency shift, linewidth, structural stability and coupling of normal modes of vibrations of free-standing graphene using a combination of lattice dynamics and molecular dynamics (MD). The in-plane lattice parameter shows a thermal contraction upto 1300 K and it expands thereafter. Frequency of the bending mode (ZA) becomes imaginary in the quasi-harmonic dispersion at higher temperatures, suggestive of a structural instability. However, the frequency of the ZA mode becomes real in the dispersion obtained from MD. Dynamical stability to the structure is restored by strong anharmonic coupling of phonon modes which is automatically incorporated in the MD simulations, whereas it is ignored in the quasi-harmonic dispersion. The mode resolved phonon spectra at Γ point show a blue-shift of degenerate longitudinal and transverse (LO/TO) optic modes. The blue-shift observed in canonical (NVT) and isobaric–isothermal (NPT) ensembles are more prominent than the shift predicted by quasi-harmonic approximation (QHA) due to the additional contribution from phonon–phonon coupling. The out-of-plane optic (ZO) mode frequencies are red-shifted in the QHA due to membrane-effect, whereas MD simulations show that the strong phonon–phonon coupling dominates the membrane effect leading to a blue-shift. The linewidth of LO/TO and ZO modes increases non-monotonically with temperature. The anharmonic coupling of normal modes at high symmetry points in the Brillouin zone is also discussed. read less USED (low confidence) Q. Yan, J. Wang, D. Chen, J. Gigax, and L. Shao, “Displacement cross sections of electron irradiated graphene and carbon nanotubes,” Nuclear Instruments & Methods in Physics Research Section B-beam Interactions With Materials and Atoms. 2015. link Times cited: 9 USED (low confidence) A. Sgouros, G. Kalosakas, M. Sigalas, and K. Papagelis, “Exotic carbon nanostructures obtained through controllable defect engineering,” RSC Advances. 2015. link Times cited: 8 Abstract: We numerically demonstrate the spontaneous formation of vari… read moreAbstract: We numerically demonstrate the spontaneous formation of various 3D carbon nanostructures, like multi-tube carbon nanotubes, nanopyramids, nanocubes, artificially rippled graphene, and other exotic nanomaterials, starting from graphene nanoribbons and inducing controllably engineered defects consisting of carbon adatoms or inverse Stone–Wales defects. The evolution of the initial defected planar structures towards the final 3D nanoarchitectures is obtained through molecular dynamics simulations, using different force fields to ensure the reproducibility of the derived results. The presented carbon nanostructures of different shapes, sizes, and morphologies, can be used in applications ranging from storage of hydrogen or other molecules, enhanced chemical reactions or catalysis in confined compartments, to drug delivery nanodevices and biosensors. read less USED (low confidence) J. Eapen, K. Murty, and T. Burchell, “Understanding Creep Mechanisms in Graphite with Experiments, Multiscale Simulations, and Modeling.” 2014. link Times cited: 0 Abstract: Disordering mechanisms in graphite have a long history with … read moreAbstract: Disordering mechanisms in graphite have a long history with conflicting viewpoints. Using Raman and x-ray photon spectroscopy, electron microscopy, x-ray diffraction experiments and atomistic modeling and simulations, the current project has developed a fundamental understanding of early-to-late state radiation damage mechanisms in nuclear reactor grade graphite (NBG-18 and PCEA). We show that the topological defects in graphite play an important role under neutron and ion irradiation. read less USED (low confidence) C.-J. Yu, G.-C. Ri, U.-G. Jong, Y. Choe, and S.-J. Cha, “Refined phase coexistence line between graphite and diamond from density-functional theory and van der Waals correction,” Physica B-condensed Matter. 2014. link Times cited: 26 USED (low confidence) H. Xie, F. Yin, and T. Yu, “Strain rate induced graphitization of cubic diamond film,” Applied Physics Letters. 2014. link Times cited: 5 Abstract: Using molecular dynamics simulations with a Tersoff-type for… read moreAbstract: Using molecular dynamics simulations with a Tersoff-type force field, we studied the deformation of cubic diamond film subjected to uniform strain rates at 30 K. The results show that at high strain rates, the diamond cubic phase transforms continuously to a multilayer graphene phase; and the graphitization begins from the (011) free surface and goes rapidly into the inner of the film. In this paper, we discuss the mechanism of graphitization and calculate the energy barrier of the graphitization. read less USED (low confidence) N. Pineau, “Molecular Dynamics Simulations of Shock Compressed Graphite,” Journal of Physical Chemistry C. 2013. link Times cited: 27 Abstract: We present molecular dynamic simulations of the shock compre… read moreAbstract: We present molecular dynamic simulations of the shock compression of graphite with the LCBOPII potential. The range of shock intensities covers the full range of available experimental data, including near-terapascal pressures. The results are in excellent agreement with the available DFT data and point to a graphite-diamond transition for shock pressures above 65 GPa, a value larger than the experimental data (20 to 50 GPa). The transition mechanism leads preferentially to hexagonal diamond through a diffusionless process but is submitted to irreversible regraphitization upon release: this result is in good agreement with the lack of highly ordered diamond observed in post-mortem experimental samples. Melting is found for shock pressures ranging from 200 to 300 GPa, close to the approximate LCBOPII diamond melting line. A good overall agreement is found between the calculated and experimental Hugoniot data up to 46% compression rate. read less USED (low confidence) A. Jaramillo-Botero, J. Tahir-Kheli, P. V. Allmen, and W. Goddard, “Multiscale, multiparadigm modeling for nano systems characterization and design.” 2012. link Times cited: 1 Abstract: This chapter outlines our progress toward developing a first… read moreAbstract: This chapter outlines our progress toward developing a first-principles-based hierarchical multiscale, multiparadigm modeling and simulation framework for the characterization and optimization of electronic and chemical properties of nanoscale materials and devices. In our approach, we build from the bottom-up by solving the quantum-mechanical (QM) Schrodinger equation for small systems. The results of these calculations lead to physical parameters that feed into methods capable of spanning longer length and time scale with minimum loss of accuracy. This is achieved by having higher-scale quantities self-consistently derived and optimized from the results at finer scales.
In contrast to other methods, we are strictly first-principles-based, and all of our parameters at all scales relate to physically measurable or QM-computable observables. Our approach that is applicable to the forward (materials phenomenology) and inverse (“materials by design”) problems. The inverse problem involves top-down predictions of structures and compositions at a lower scale from desired properties at a higher scale.
The advantages of our strategy over experimental- and phenomenological-based modeling and simulation approaches include the following: (1) providing access to details that are difficult or impossible to measure (e.g., excited electronic states in materials undergoing extreme conditions of pressure, temperature, etc.); (2) the ability to make useful predictions outside the range of experiments (i.e., since all calculations are ultimately related to first principles); and (3) providing sound, first-principles-based, steering for experiments. read less USED (low confidence) J. Palmer and K. Gubbins, “Atomistic models for disordered nanoporous carbons using reactive force fields,” Microporous and Mesoporous Materials. 2012. link Times cited: 75 USED (low confidence) J. Los, C. Bichara, and R. Pellenq, “Tight binding within the fourth moment approximation: Efficient implementation and application to liquid Ni droplet diffusion on graphene.” 2011. link Times cited: 9 Abstract: (Received 8 February 2011; revised manuscript received 13 Ma… read moreAbstract: (Received 8 February 2011; revised manuscript received 13 May 2011; published 31 August 2011)Application of the fourth moment approximation (FMA) to the local density of states within a tight bindingdescription to build a reactive, interatomic interaction potential for use in large scale molecular simulations,is a logical and significant step forward to improve the second moment approximation, standing at the basisof several, widely used (semi-)empirical interatomic interaction models. In this paper we present a sufficientlydetailed description of the FMA and its technical implications, containing the essential elements for an efficientimplementationinasimulationcode.Usingarecent,existingFMA-basedmodelforC-Nisystems,weinvestigatedthesizedependenceofthediffusionofaliquidNiclusteronagraphenesheetandfindapowerlawdependenceofthediffusionconstantontheclustersize(numberofclusteratoms)withanexponentverycloseto−2 read less USED (low confidence) H. Ohnishi, E. Inami, and J. Kanasaki, “Intact-sheet double-layer ablation induced by femtosecond-laser excitation of graphite,” Surface Science. 2011. link Times cited: 3 USED (low confidence) G. Chevrot, E. Bourasseau, N. Pineau, and J. Maillet, “Molecular dynamics simulations of nanocarbons at high pressure and temperature,” Carbon. 2009. link Times cited: 16 USED (low confidence) H. Bu, Y. Chen, M. Zou, H. Yi, K. Bi, and Z. Ni, “Atomistic simulations of mechanical properties of graphene nanoribbons,” Physics Letters A. 2009. link Times cited: 145 USED (low confidence) N. A. Katcho et al., “Structure of carbon nanospheres prepared by chlorination of cobaltocene: Experiment and modeling,” Physical Review B. 2008. link Times cited: 6 Abstract: With the concourse of a variety of experimental techniques (… read moreAbstract: With the concourse of a variety of experimental techniques (neutron diffraction, x-ray photoelectron spectroscopy, $^{13}\text{C}$ nuclear magnetic resonance, electron microscopy, and Raman spectroscopy) and a combination of reverse Monte Carlo, molecular dynamics, and Monte Carlo simulations, we propose a model for the microscopic structure of a sample of carbon nanospheres obtained from chlorination of cobaltocene. The sample, which exhibits a high porosity, is shown to be formed by a series of interconnected sheets of graphene. Despite the large degree $(\ensuremath{\approx}80%)$ of $s{p}^{2}$ hybridization shown by carbon atoms, there is a non-negligible amount of $s{p}^{3}$-bonded carbons, some of them acting as links between graphene sheets. The transmission electron microscopy images simulated from the microscopic structure, which is extracted from the neutron diffraction data by a mixed reverse Monte Carlo\char21{}molecular dynamics/Monte Carlo procedure, agree remarkably well with the experimental results. read less USED (low confidence) J. Yim, M. Falk, and I. Boyd, “Modeling low energy sputtering of hexagonal boron nitride by xenon ions,” Journal of Applied Physics. 2008. link Times cited: 20 Abstract: The sputtering of hexagonal boron nitride due to low energy … read moreAbstract: The sputtering of hexagonal boron nitride due to low energy xenon ion bombardments occurs in various applications including fabrication of cubic boron nitride and erosion of Hall thruster channel walls. At low ion energies, accurate experimental characterization of sputtering increases in difficulty due to the low yields involved. A molecular dynamics model is employed to simulate the sputtering process and to calculate sputter yields for ion energies ranging from 10 to 350 eV. The results are compared to experimental data and a semiempirical expression developed by Bohdansky [Nucl. Instrum. Methods Phys. Res. B 2, 587 (1984)] is found to adequately describe the simulation data. Surface temperature effects are also investigated, and the sputter yield at 850 K is approximately twice that at 423 K. read less USED (low confidence) J. Yim, M. Falk, M. Keidar, and I. Boyd, “Calculation of Boron Nitride Sputter Yields Under Low Energy Xenon Ion Bombardment.” 2007. link Times cited: 4 Abstract: An accurate description of the sputter yield of boron nitrid… read moreAbstract: An accurate description of the sputter yield of boron nitride (BN) from xenon ion bombardment at low energies is needed for improving the prediction capabilities of Hall thruster erosion models and in turn for lifetime prediction models. However, sputter yield data at low (< 300 eV) energies does not exist. The molecular dynamics method is employed to model the sputtering of BN at low energies. The results are compared to existing experimental data at higher energies. A qualitative comparison with a quantumstatistical model is also performed. read less USED (low confidence) Y. Chen et al., “The Dual Role of Interlayer Crosslinks Leads to an Abnormal Behavior of Interlayer Thermal Resistance in Multilayer Graphene,” SSRN Electronic Journal. 2022. link Times cited: 4 USED (low confidence) O. Hod, “Interlayer Interactions in Low-Dimensional Layered Hetero-structures: Modeling and Applications,” Handbook of Materials Modeling. 2020. link Times cited: 0 USED (low confidence) A. Sircar and P. Patra, “Rolling and Sliding Resistance as Carbon Nanotubes are Driven on a Graphene Sheet.” 2020. link Times cited: 0 USED (low confidence) R. Lindsey, M. Kroonblawd, L. Fried, and N. Goldman, “Force Matching Approaches to Extend Density Functional Theory to Large Time and Length Scales,” Computational Approaches for Chemistry Under Extreme Conditions. 2019. link Times cited: 6 USED (low confidence) S. Winczewski, M. Y. Shaheen, and J. Rybicki, “Interatomic potential suitable for the modeling of penta-graphene: Molecular statics/molecular dynamics studies,” Carbon. 2018. link Times cited: 34 USED (low confidence) J. Baimova, L. Rysaeva, and A. Rudskoy, “Deformation behavior of diamond-like phases: Molecular dynamics simulation,” Diamond and Related Materials. 2018. link Times cited: 25 USED (low confidence) S. Dmitriev, J. Baimova, E. Korznikova, and A. Chetverikov, “Nonlinear Excitations in Graphene and Other Carbon Nano-Polymorphs.” 2018. link Times cited: 2 USED (low confidence) B. Schultrich, “Structure of Amorphous Carbon.” 2018. link Times cited: 2 USED (low confidence) A. Soloviev, R. Gruzdev, A. V. Derkun, and E. Lähderanta, “Identification of Graphene Properties in the Framework of Molecular Dynamics.” 2017. link Times cited: 0 USED (low confidence) F. Gargiulo, “The role of disorder in the electronic and transport properties of monolayer and bilayer graphene.” 2015. link Times cited: 0 Abstract: This thesis is devoted to the computational study of the ele… read moreAbstract: This thesis is devoted to the computational study of the electronic and transport properties of monolayer and bilayer graphene in the presence of disorder arising from both topological and point defects. Among the former, we study grain boundaries in monolayer graphene and stacking domain boundaries in bilayer graphene, whereas among the latter we study hydrogen atoms covalently bound on the graphene crystal lattice. The electronic spectrum of disordered graphene has been studied within a tight-binding framework, which has been coupled to the Landauer-Buttiker theory and Green?s function techniques in order to have access to the properties of coherent transport of graphene charge carriers. We assess the low-energy equilibrium structures of defective graphene by a combination of ab initio density functional theory, classical potentials, and Monte Carlo methods. We study periodic grain boundaries in monolayer graphene and individuate two classes of defects with opposite effects in terms of scattering of low-energy charge carriers. One class, unexpectedly, is highly reflecting in the limit of low defect density, whereas another is highly transparent. Subsequently, we study disordered grain boundaries in order to predict the intrinsic conductance of realistic polycrystalline graphene samples. In two related works, conducted in collaboration with experimentalists, we identify the atomic structure of periodic grain boundaries imaged by scanning tunneling microscopy, and discuss the valley-filtering capabilities of a line defect of graphene that can be grown in a controllable manner. Next, we investigate the electronic transport of graphene with realistic hydrogen adsorbates, whose equilibrium configurations are obtained by means of Monte Carlo simulations. We find that the conductance of graphene dramatically increases upon formation of cluster adatoms, which we predict to happen spontaneously at room temperature. This is due to the non- resonant nature of a large fraction of hydrogen clusters in the room-temperature distribution, which we further elucidate by means of an analytically solvable model. Finally, we study the behavior, in terms of structural and electronic properties, of twisted bilayer graphene in the limit of zero twist angle. We find a critical angle below which the system arranges in a triangular superlattice of Bernal-stacking domains, separated by a hexagonal network of stacking domain boundaries. The presence of stacking domain boundaries is at the base of our interpretation of an experiment reporting oscillations in the electrical conductance of bilayer graphene subjected to mechanical indentation. read less USED (low confidence) Y. Zhao, L. Peng, and G. Yu, “Electrochemical Hierarchical Composites.” 2015. link Times cited: 2 USED (low confidence) V. Hizhnyakov, M. Haas, A. Shelkan, and M. Klopov, “Standing and Moving Discrete Breathers with Frequencies Above the Phonon Spectrum.” 2015. link Times cited: 9 USED (low confidence) M. Katsnelson, “Graphene: Gauge fields and strain engineering.” 2012. link Times cited: 0 USED (low confidence) M. Katsnelson, “Crystal lattice dynamics, structure and thermodynamics.” 2012. link Times cited: 1 USED (low confidence) M. Katsnelson, “Graphene: The electronic structure of ideal graphene.” 2012. link Times cited: 4 USED (low confidence) M. Katsnelson, “Graphene: Edges, nanoribbons and quantum dots.” 2012. link Times cited: 0 USED (low confidence) M. Katsnelson, “Graphene: Electron states in a magnetic field.” 2012. link Times cited: 0 USED (low confidence) N. Marks, “Amorphous Carbon and Related Materials.” 2010. link Times cited: 7 USED (low confidence) L. Ghiringhelli and E. Meijer, “Liquid carbon: Freezing line and structure near freezing.” 2010. link Times cited: 5 NOT USED (low confidence) X. Jiang, H. Sun, K. Choudhary, H. Zhuang, and Q. Nian, “Interpretable Ensemble Learning for Materials Property Prediction with Classical Interatomic Potentials: Carbon as an Example,” ArXiv. 2023. link Times cited: 0 Abstract: Machine learning (ML) is widely used to explore crystal mate… read moreAbstract: Machine learning (ML) is widely used to explore crystal materials and predict their properties. However, the training is time-consuming for deep-learning models, and the regression process is a black box that is hard to interpret. Also, the preprocess to transfer a crystal structure into the input of ML, called descriptor, needs to be designed carefully. To efficiently predict important properties of materials, we propose an approach based on ensemble learning consisting of regression trees to predict formation energy and elastic constants based on small-size datasets of carbon allotropes as an example. Without using any descriptor, the inputs are the properties calculated by molecular dynamics with 9 different classical interatomic potentials. Overall, the results from ensemble learning are more accurate than those from classical interatomic potentials, and ensemble learning can capture the relatively accurate properties from the 9 classical potentials as criteria for predicting the final properties. read less NOT USED (low confidence) A. Aghajamali and A. Karton, “Can force fields developed for carbon nanomaterials describe the isomerization energies of fullerenes,” Chemical Physics Letters. 2021. link Times cited: 8 NOT USED (low confidence) X. Huo, L. Song, Y. Xie, L. Zhang, and M. Yang, “PVT relation of the main products of 1,3,5-triamino-2,4,6-trinitrobenzene explosive reactions through a molecular dynamics approach,” Chemical Physics. 2021. link Times cited: 0 NOT USED (low confidence) S. R. González et al., “Diradicals acting through diamagnetic phenylene vinylene bridges: Raman spectroscopy as a probe to characterize spin delocalization.,” The Journal of chemical physics. 2014. link Times cited: 5 Abstract: We present a complete Raman spectroscopic study in two struc… read moreAbstract: We present a complete Raman spectroscopic study in two structurally well-defined diradical species of different lengths incorporating oligo p-phenylene vinylene bridges between two polychlorinated triphenylmethyl radical units, a disposition that allows sizeable conjugation between the two radicals through and with the bridge. The spectroscopic data are interpreted and supported by quantum chemical calculations. We focus the attention on the Raman frequency changes, interpretable in terms of: (i) bridge length (conjugation length); (ii) bridge conformational structure; and (iii) electronic coupling between the terminal radical units with the bridge and through the bridge, which could delineate through-bond spin polarization, or spin delocalization. These items are addressed by using the "oligomer approach" in conjunction with pressure and temperature dependent Raman spectroscopic data. In summary, we have attempted to translate the well-known strategy to study the electron (charge) structure of π-conjugated molecules by Raman spectroscopy to the case of electron (spin) interactions via the spin delocalization mechanism. read less NOT USED (low confidence) J. Los, L. Ghiringhelli, E. Meijer, and A. Fasolino, “Improved long-range reactive bond-order potential for carbon. I. Construction (Correction on vol 72, pg 214102, 2005),” Acta Crystallographica Section B-structural Science. 2005. link Times cited: 181 Abstract: We present LCBOPII, an improvement of the long-range carbon … read moreAbstract: We present LCBOPII, an improvement of the long-range carbon bond-order potential (LCBOP) by Los and Fasolino [Phys. Rev. B 68, 024107 (2003)]. LCBOPII contains a coordination dependent medium range term for bond distances between 1.7 and $4\phantom{\rule{0.3em}{0ex}}\mathrm{\AA{}}$, meant to reproduce the dissociation energy curves for single, double, and triple bonds and improve the reactive properties as well as the description of the liquid and of low coordinated phases. Other features of LCBOPII are a coordination dependent angular correlation, a correction for antibonding states, and a conjugation dependent torsional interaction based on ab initio calculations of the torsional barriers for a set of molecular configurations. We present results for the geometry and energetics of the graphite-to-diamond transformation and of the vacancy in diamond and graphite as well as the prediction of the energy barrier of the 5-77-5 defect in graphite and graphene for which ab initio results are available only for unsuitably small samples. In the accompanying paper (Ghiringhelli et al., Phys. Rev. B 72, 214103 (2005) we use LCBOPII to evaluate several properties, including the equation of state, of liquid carbon. read less NOT USED (high confidence) S. Eskandari, J. Koltai, I. László, M. Vaezi, and J. Kürti, “Formation of nanoribbons by carbon atoms confined in a single-walled carbon nanotube-A molecular dynamics study.,” The Journal of chemical physics. 2023. link Times cited: 0 Abstract: Carbon nanotubes can serve as one-dimensional nanoreactors f… read moreAbstract: Carbon nanotubes can serve as one-dimensional nanoreactors for the in-tube synthesis of various nanostructures. Experimental observations have shown that chains, inner tubes, or nanoribbons can grow by the thermal decomposition of organic/organometallic molecules encapsulated in carbon nanotubes. The result of the process depends on the temperature, the diameter of the nanotube, and the type and amount of material introduced inside the tube. Nanoribbons are particularly promising materials for nanoelectronics. Motivated by recent experimental results observing the formation of carbon nanoribbons inside carbon nanotubes, molecular dynamics calculations were performed with the open source LAMMPS code to investigate the reactions between carbon atoms confined within a single-walled carbon nanotube. Our results show that the interatomic potentials behave differently in quasi-one-dimensional simulations of nanotube-confined space than in three-dimensional simulations. In particular, the Tersoff potential performs better than the widely used Reactive Force Field potential in describing the formation of carbon nanoribbons inside nanotubes. We also found a temperature window where the nanoribbons were formed with the fewest defects, i.e., with the largest flatness and the most hexagons, which is in agreement with the experimental temperature range. read less NOT USED (high confidence) M. Qamar, M. Mrovec, Y. Lysogorskiy, A. Bochkarev, and R. Drautz, “Atomic Cluster Expansion for Quantum-Accurate Large-Scale Simulations of Carbon.,” Journal of chemical theory and computation. 2022. link Times cited: 17 Abstract: We present an atomic cluster expansion (ACE) for carbon that… read moreAbstract: We present an atomic cluster expansion (ACE) for carbon that improves over available classical and machine learning potentials. The ACE is parametrized from an exhaustive set of important carbon structures over extended volume and energy ranges, computed using density functional theory (DFT). Rigorous validation reveals that ACE accurately predicts a broad range of properties of both crystalline and amorphous carbon phases while being several orders of magnitude more computationally efficient than available machine learning models. We demonstrate the predictive power of ACE on three distinct applications: brittle crack propagation in diamond, the evolution of amorphous carbon structures at different densities and quench rates, and the nucleation and growth of fullerene clusters under high-pressure and high-temperature conditions. read less NOT USED (high confidence) Z. Fthenakis, I. Petsalakis, V. Tozzini, and N. Lathiotakis, “Evaluating the performance of ReaxFF potentials for sp2 carbon systems (graphene, carbon nanotubes, fullerenes) and a new ReaxFF potential,” Frontiers in Chemistry. 2022. link Times cited: 7 Abstract: We study the performance of eleven reactive force fields (Re… read moreAbstract: We study the performance of eleven reactive force fields (ReaxFF), which can be used to study sp2 carbon systems. Among them a new hybrid ReaxFF is proposed combining two others and introducing two different types of C atoms. The advantages of that potential are discussed. We analyze the behavior of ReaxFFs with respect to 1) the structural and mechanical properties of graphene, its response to strain and phonon dispersion relation; 2) the energetics of (n, 0) and (n, n) carbon nanotubes (CNTs), their mechanical properties and response to strain up to fracture; 3) the energetics of the icosahedral C60 fullerene and the 40 C40 fullerene isomers. Seven of them provide not very realistic predictions for graphene, which made us focusing on the remaining, which provide reasonable results for 1) the structure, energy and phonon band structure of graphene, 2) the energetics of CNTs versus their diameter and 3) the energy of C60 and the trend of the energy of the C40 fullerene isomers versus their pentagon adjacencies, in accordance with density functional theory (DFT) calculations and/or experimental data. Moreover, the predicted fracture strain, ultimate tensile strength and strain values of CNTs are inside the range of experimental values, although overestimated with respect to DFT. However, they underestimate the Young’s modulus, overestimate the Poisson’s ratio of both graphene and CNTs and they display anomalous behavior of the stress - strain and Poisson’s ratio - strain curves, whose origin needs further investigation. read less NOT USED (high confidence) H. Zhang and J. Guilleminot, “A Riemannian stochastic representation for quantifying model uncertainties in molecular dynamics simulations,” Computer Methods in Applied Mechanics and Engineering. 2022. link Times cited: 2 NOT USED (high confidence) S. Banik et al., “CEGANN: Crystal Edge Graph Attention Neural Network for multiscale classification of materials environment,” npj Computational Materials. 2022. link Times cited: 10 NOT USED (high confidence) Z. El-Machachi, M. Wilson, and V. L. Deringer, “Exploring the configurational space of amorphous graphene with machine-learned atomic energies,” Chemical Science. 2022. link Times cited: 4 Abstract: Two-dimensionally extended amorphous carbon (“amorphous grap… read moreAbstract: Two-dimensionally extended amorphous carbon (“amorphous graphene”) is a prototype system for disorder in 2D, showing a rich and complex configurational space that is yet to be fully understood. Here we explore the nature of amorphous graphene with an atomistic machine-learning (ML) model. We create structural models by introducing defects into ordered graphene through Monte-Carlo bond switching, defining acceptance criteria using the machine-learned local, atomic energies associated with a defect, as well as the nearest-neighbor (NN) environments. We find that physically meaningful structural models arise from ML atomic energies in this way, ranging from continuous random networks to paracrystalline structures. Our results show that ML atomic energies can be used to guide Monte-Carlo structural searches in principle, and that their predictions of local stability can be linked to short- and medium-range order in amorphous graphene. We expect that the former point will be relevant more generally to the study of amorphous materials, and that the latter has wider implications for the interpretation of ML potential models. read less NOT USED (high confidence) Z. You, J. Xiao, Q. Mao, S. Ye, and Q. Zhong, “Influence mechanism of Nano-Fe2O3 on amorphous carbon graphitisation in molecular view via ReaxFF MD simulation,” Molecular Simulation. 2021. link Times cited: 3 Abstract: ABSTRACT Nano-Fe2O3/C composites are widely used in the elec… read moreAbstract: ABSTRACT Nano-Fe2O3/C composites are widely used in the electrochemical energy storage field. Preparing nano-Fe2O3/C composites via graphitising the amorphous carbon inserting nano-Fe2O3 particles is potential if the influence mechanism of nano-Fe2O3 on the graphitisation of amorphous carbon is explored in-depth. Here, an amorphous carbon model (a-C model) and a nano-Fe2O3-inserting model (C\Fe2O3 model) were built via the liquid-quench method, and the reaction of Fe2O3 and C during graphitisation was explored via the reactive force field (ReaxFF) simulation. The results showed that nano-Fe2O3 could inhibit the graphitisation of amorphous carbon, and the mechanism was revealed. The Fe2O3 molecules collided with the aromatic carbon layer because of the thermal motion, which caused the breaking of the carbon layer and the generation of CO2 and Fe. Certain Fe reduced from Fe2O3 destroyed the aromatic carbon layers by the strong affinity between Fe and C atoms and generated intercalation compounds (FeCx). Furthermore, the regularisation and stacking of large carbon layers were impeded. Thus, the graphitisation of amorphous carbon was inhibited. read less NOT USED (high confidence) C.-gen Qian, B. Mclean, D. Hedman, and F. Ding, “A comprehensive assessment of empirical potentials for carbon materials,” APL Materials. 2021. link Times cited: 22 Abstract: Carbon materials and their unique properties have been exten… read moreAbstract: Carbon materials and their unique properties have been extensively studied by molecular dynamics, thanks to the wide range of available carbon bond order potentials (CBOPs). Recently, with the increase in popularity of machine learning (ML), potentials such as Gaussian approximation potential (GAP), trained using ML, can accurately predict results for carbon. However, selecting the right potential is crucial as each performs differently for different carbon allotropes, and these differences can lead to inaccurate results. This work compares the widely used CBOPs and the GAP-20 ML potential with density functional theory results, including lattice constants, cohesive energies, defect formation energies, van der Waals interactions, thermal stabilities, and mechanical properties for different carbon allotropes. We find that GAP-20 can more accurately predict the structure, defect properties, and formation energies for a variety of crystalline phase carbon compared to CBOPs. Importantly, GAP-20 can simulate the thermal stability of C60 and the fracture of carbon nanotubes and graphene accurately, where CBOPs struggle. However, similar to CBOPs, GAP-20 is unable to accurately account for van der Waals interactions. Despite this, we find that GAP-20 outperforms all CBOPs assessed here and is at present the most suitable potential for studying thermal and mechanical properties for pristine and defective carbon. read less NOT USED (high confidence) C. Silva, P. Chrostoski, and P. Fraundorf, “DFT study of ‘unlayered graphene solid’ formation, in liquid carbon droplets at low pressures,” MRS Advances. 2021. link Times cited: 1 Abstract: This atomistic modeling study is companion to new experiment… read moreAbstract: This atomistic modeling study is companion to new experimental work on carbon vapor slow-cooled in (a) the laboratory and (b) the atmosphere of ancient carbon-synthesizing stars. It specifically follows up on TEM clues about the nucleation of unlayered graphene sheets in a solidifying carbon liquid, to show that 5 atom loops may help explain evidence for faceted pentacones in a slow-cooled melt. This is also first in a series of modeling studies that may open the door to laboratory studies of (i) condensation in cool-giant star atmospheres and (ii) liquid carbon at low pressures. read less NOT USED (high confidence) B. Rice, W. Mattson, J. Larentzos, and E. Byrd, “Heuristics for chemical species identification in dense systems.,” The Journal of chemical physics. 2020. link Times cited: 6 Abstract: A new approach to identify chemical species from molecular d… read moreAbstract: A new approach to identify chemical species from molecular dynamics (MD) simulations of reacting materials under extreme temperatures and pressures is presented. The approach is based on bond-distance and vibrational criteria, derived from the examination of atomic behavior during a density functional theory MD simulation of an overdriven shock of the explosive pentaerythritol tetranitrate. For comparison, the trajectory was analyzed using popular bonding criteria commonly used in analysis of reactive MD simulations, including distance, distance-time, and bond-order criteria. Cluster analyses using the new time-dependent bond definition approach presented here and a bond-order approach revealed that species and their corresponding lifetimes were strongly dependent on the chosen approach, indicating significant implications for the development of chemical mechanisms and chemical kinetics models using the results of reactive MD simulations. read less NOT USED (high confidence) C. Herrero and R. Ramírez, “Isotopic effects in structural properties of graphene,” The European Physical Journal B. 2020. link Times cited: 3 NOT USED (high confidence) N. Sheremetyeva, M. Lamparski, C. Daniels, B. V. Troeye, and V. Meunier, “Machine-learning models for Raman spectra analysis of twisted bilayer graphene,” Carbon. 2020. link Times cited: 20 NOT USED (high confidence) P. Rowe, V. L. Deringer, P. Gasparotto, G. Csányi, and A. Michaelides, “An accurate and transferable machine learning potential for carbon.,” The Journal of chemical physics. 2020. link Times cited: 120 Abstract: We present an accurate machine learning (ML) model for atomi… read moreAbstract: We present an accurate machine learning (ML) model for atomistic simulations of carbon, constructed using the Gaussian approximation potential (GAP) methodology. The potential, named GAP-20, describes the properties of the bulk crystalline and amorphous phases, crystal surfaces, and defect structures with an accuracy approaching that of direct ab initio simulation, but at a significantly reduced cost. We combine structural databases for amorphous carbon and graphene, which we extend substantially by adding suitable configurations, for example, for defects in graphene and other nanostructures. The final potential is fitted to reference data computed using the optB88-vdW density functional theory (DFT) functional. Dispersion interactions, which are crucial to describe multilayer carbonaceous materials, are therefore implicitly included. We additionally account for long-range dispersion interactions using a semianalytical two-body term and show that an improved model can be obtained through an optimization of the many-body smooth overlap of atomic positions descriptor. We rigorously test the potential on lattice parameters, bond lengths, formation energies, and phonon dispersions of numerous carbon allotropes. We compare the formation energies of an extensive set of defect structures, surfaces, and surface reconstructions to DFT reference calculations. The present work demonstrates the ability to combine, in the same ML model, the previously attained flexibility required for amorphous carbon [V. L. Deringer and G. Csányi, Phys. Rev. B 95, 094203 (2017)] with the high numerical accuracy necessary for crystalline graphene [Rowe et al., Phys. Rev. B 97, 054303 (2018)], thereby providing an interatomic potential that will be applicable to a wide range of applications concerning diverse forms of bulk and nanostructured carbon. read less NOT USED (high confidence) M. A. Caro, G. Csányi, T. Laurila, and V. L. Deringer, “Machine learning driven simulated deposition of carbon films: From low-density to diamondlike amorphous carbon,” Physical Review B. 2020. link Times cited: 29 Abstract: © 2020 American Physical Society. Amorphous carbon (a-C) mat… read moreAbstract: © 2020 American Physical Society. Amorphous carbon (a-C) materials have diverse interesting and useful properties, but the understanding of their atomic-scale structures is still incomplete. Here, we report on extensive atomistic simulations of the deposition and growth of a-C films, describing interatomic interactions using a machine learning (ML) based Gaussian approximation potential model. We expand widely on our initial work [M. A. Caro, Phys. Rev. Lett. 120, 166101 (2018)PRLTAO0031-900710.1103/PhysRevLett.120.166101] by now considering a broad range of incident ion energies, thus modeling samples that span the entire range from low-density (sp2-rich) to high-density (sp3-rich, "diamondlike") amorphous forms of carbon. Two different mechanisms are observed in these simulations, depending on the impact energy: low-energy impacts induce sp- and sp2-dominated growth directly around the impact site, whereas high-energy impacts induce peening. Furthermore, we propose and apply a scheme for computing the anisotropic elastic properties of the a-C films. Our work provides fundamental insight into this intriguing class of disordered solids, as well as a conceptual and methodological blueprint for simulating the atomic-scale deposition of other materials with ML driven molecular dynamics. read less NOT USED (high confidence) M. Wen and E. Tadmor, “Uncertainty quantification in molecular simulations with dropout neural network potentials,” npj Computational Materials. 2020. link Times cited: 46 NOT USED (high confidence) Y. D. Fomin and V. Brazhkin, “Comparative study of melting of graphite and graphene,” Carbon. 2020. link Times cited: 31 NOT USED (high confidence) M. Wen and E. Tadmor, “Hybrid neural network potential for multilayer graphene,” Physical Review B. 2019. link Times cited: 40 Abstract: Monolayer and multilayer graphene are promising materials fo… read moreAbstract: Monolayer and multilayer graphene are promising materials for applications such as electronic devices, sensors, energy generation and storage, and medicine. In order to perform large-scale atomistic simulations of the mechanical and thermal behavior of graphene-based devices, accurate interatomic potentials are required. Here, we present a new interatomic potential for multilayer graphene structures referred to as "hNN--Gr$_x$." This hybrid potential employs a neural network to describe short-range interactions and a theoretically-motivated analytical term to model long-range dispersion. The potential is trained against a large dataset of monolayer graphene, bilayer graphene, and graphite configurations obtained from ab initio total-energy calculations based on density functional theory (DFT). The potential provides accurate energy and forces for both intralayer and interlayer interactions, correctly reproducing DFT results for structural, energetic, and elastic properties such as the equilibrium layer spacing, interlayer binding energy, elastic moduli, and phonon dispersions to which it was not fit. The potential is used to study the effect of vacancies on thermal conductivity in monolayer graphene and interlayer friction in bilayer graphene. The potential is available through the OpenKIM interatomic potential repository at \url{this https URL}. read less NOT USED (high confidence) H. Wang, J. Guilleminot, and C. Soize, “Modeling uncertainties in molecular dynamics simulations using a stochastic reduced-order basis,” Computer Methods in Applied Mechanics and Engineering. 2019. link Times cited: 14 NOT USED (high confidence) L. Bellucci, T. Cavallucci, and V. Tozzini, “From the Buffer Layer to Graphene on Silicon Carbide: Exploring Morphologies by Computer Modeling,” Frontiers in Materials. 2019. link Times cited: 10 Abstract: Epitaxial graphene grown by thermal Si decomposition of Sili… read moreAbstract: Epitaxial graphene grown by thermal Si decomposition of Silicon Carbide appears in different morphological variants, depending on the production conditions: the strongly rugged buffer layer, retaining a considerable amount of sp3 hybridized buffer layer, the softly corrugated graphene monolayer and the rather flat quasi free standing monolayer with sparse small pits pinned to localized electronic states. Therefore, graphene on SiC is not a single material, but a set of materials with different morphologies depending on the environmental conditions during the synthesis. In all cases the distortion from the ideal flat structure seem to follow to some extent specific symmetries, which appear to preserve some memory of the interaction with the SiC bulk, even in the cases in which the sheet is substantially decoupled from it. Defects bear interesting properties, e.g. localized hot spots of reactivity and localized electronic states with specific energy depending on their nature and morphology, while their possible symmetric location is an added value for applications. Therefore, being capable of controlling the morphology, concentration, symmetry and location of the defects would allow tailoring this material for specific applications. Based on ab initio calculations and simulations, we first describe in detail the morphology of the different systems, and, subsequently, we formulate hypotheses on the relationship between morphology and the formation process. We finally suggest future simulation studies capable of revealing the still unclear steps. These should give indication on how to tune the environmental conditions to control the final morphology of the sample and specifically design this material. read less NOT USED (high confidence) A. Cupo, D. Tristant, K. Rego, and V. Meunier, “Theoretical analysis of spectral lineshapes from molecular dynamics,” npj Computational Materials. 2019. link Times cited: 6 NOT USED (high confidence) H. Almisbahi, “Analysing graphene vibrations via molecular dynamics simulations and dimension reduction techniques.” 2019. link Times cited: 0 Abstract: Graphene was first isolated in the lab in 2003 and this work… read moreAbstract: Graphene was first isolated in the lab in 2003 and this work was first published in 2004 by a research team at The University of Manchester. Since that date, graphene research has exploded due to its special properties. Phonons and molecular dynamic simulation provide valuable tools to study the molecular systems under different structure forms. They are helpful to study graphene ribbons and defects. On the other hand, many machine learning techniques were extensively used to analyse the enormous amounts of data resulted from the molecular simulations.
As such, this thesis aimed to use one of the machine learning techniques to study phonons of graphene with single vacancy defect and graphene armchair nanoribbons. PCA can be used to transform the atomic velocities into orthogonal eigenvectors such that each eigenvector represents one of the phonon modes of graphene. This is helpful to visualize the atomic motion of a specific phonon mode. To provide orthogonal eigenvectors, PCA needs the data to be of gaussian distribution. The atomic velocities resulted from the molecular simulations follow gaussian distribution at the equilibrium state. Hence, the assumption of gaussian distribution needed by PCA is achieved. However, only some of the phonon modes can be calculated from the atomic velocities in their real space. Most of the phonon modes are calculated after transforming the atomic velocities to a reciprocal space (k space) using spatial Fourier transform. The k space atomic velocities are not following gaussian distribution. This thesis introduced a novel method to use PCA to isolate and visualize the phonon modes extracted from the k space velocities.
To prove the feasibility of using PCA to isolate k space phonons, we conducted classical molecular simulations of graphene with different structures. The effect of single vacancy defect on graphene phonons was studied in comparison to the perfect graphene. In addition, the effect of the armchair ribbon width on graphene phonon modes was investigated.
The results of the conducted molecular simulations were used with PCA to visualize some of the phonon modes of pristine graphene and armchair nanoribbons of graphene. We used PCA to present the evolution of the atomic motion of specific k space phonon modes of armchair ribbons: the first overtone of TA phonon mode and the highest overtone of TO phonon mode. The presented motions showed that the breathing like mode is a transition state between two opposite atomic motions of TA mode.
In the method we introduced using PCA, we used the eigenvectors with the lowest eigenvalues to study the Fourier transformed atomic velocities. This method rotated the k space atomic velocities into the eigenvectors with the lowest eigenvalues which helped to isolate and visualize the k space phonon modes. read less NOT USED (high confidence) S. Thomas, K. Ajith, S. U. Lee, and M. C. Valsakumar, “Assessment of the mechanical properties of monolayer graphene using the energy and strain-fluctuation methods,” RSC Advances. 2018. link Times cited: 28 Abstract: Molecular statics and dynamics simulations were performed to… read moreAbstract: Molecular statics and dynamics simulations were performed to investigate the mechanical properties of a monolayer graphene sheet using an efficient energy method and strain-fluctuation method. Using the energy method, we observed that the mechanical properties of an infinite graphene sheet are isotropic, whereas for a finite sheet, they are anisotropic. This work is the first to report the temperature-dependent elastic constants of graphene between 100 and 1000 K using the strain-fluctuation method. We found that the out-of-plane thermal excursions in a graphene membrane lead to strong anharmonic behavior, which allows large deviations from isotropic elasticity. The computed Young's modulus and Poisson's ratio of a sheet with an infinite spatial extent are 0.939 TPa and 0.223, respectively. We also found that graphene sheets with both finite and infinite spatial extent satisfy the Born elastic stability conditions. We extracted the variation in bending modulus with the system size at zero kelvin (0.83 eV) using a formula derived from the Foppl–von Karman approach. When the temperature increases, the Young's modulus of the sample decreases, which effectively reduces the longitudinal and shear wave velocities. read less NOT USED (high confidence) C. Guedj, L. Jaillet, F. Rousse, and S. Redon, “Atomistic Modelling and Simulation of Transmission Electron Microscopy Images: Application to Intrinsic Defects of Graphene,” International Conference on Simulation and Modeling Methodologies, Technologies and Applications. 2018. link Times cited: 1 Abstract: The characterization of advanced materials and devices in th… read moreAbstract: The characterization of advanced materials and devices in the nanometer range requires complex tools to understand the precise links between structure and properties. This paper demonstrates that the modelling of graphene-based defects can be obtained efficiently for various atomic arrangements using the Brenner module of the SAMSON software platform. The signatures of all kinds of defects are computed in terms of energy and simulated scanning transmission electron microscopy images. The results are in good agreement with the majority of the available theoretical and experimental data. This original methodology is an excellent compromise between the speed and the precision required by the semiconductor industry and opens the possibility of realistic in-silico research conjugated to the experimental nanocharacterization of these promising materials. We propose a novel approach to compare the agreement between experiment and simulation by using the projected radial distribution function. The maximum projected Euclidian distance between the model and the experiment is always better than 100 pm. read less NOT USED (high confidence) M. Kroonblawd and N. Goldman, “Mechanochemical formation of heterogeneous diamond structures during rapid uniaxial compression in graphite,” Physical Review B. 2018. link Times cited: 18 Abstract: We predict mechanochemical formation of heterogeneous diamon… read moreAbstract: We predict mechanochemical formation of heterogeneous diamond structures from rapid uniaxial compression in graphite using quantum molecular dynamics simulations. Ensembles of simulations reveal the formation of different diamond-like products starting from thermal graphite crystal configurations. We identify distinct classes of final products with characteristic probabilities of formation, stress states, and electrical properties, and show through simulations of rapid quenching that these products are nominally stable and can be recovered at room temperature and pressure. Some of the diamond products exhibit significant disorder and partial closure of the HOMOLUMO gap. Seeding atomic vacancies in graphite significantly biases toward forming products with small HOMO-LUMO gaps. We show that a strong correlation between the HOMO-LUMO gap and disorder in tetrahedral bonding configurations informs which kinds of structural defects are associated with gap closure. The rapid diffusionless transformation of graphite is found to lock vacancy defects into the final diamond structure, resulting in configurations that prevent sp3 bonding and lead to localized HOMO and LUMO states with a small gap. read less NOT USED (high confidence) S. Goel and A. Stukowski, “Comment on ‘Incipient plasticity of diamond during nanoindentation’ by C. Xu, C. Liu and H. Wang, RSC Advances, 2017, 7, 36093,” RSC Advances. 2018. link Times cited: 4 Abstract: A recent molecular dynamics simulation study on nanoindentat… read moreAbstract: A recent molecular dynamics simulation study on nanoindentation of diamond carried out by Xu et al.1 has reported observation of the presence of a controversial hexagonal lonsdaleite phase of carbon in the indentation area. In this comment, we question the reported observation and attribute this anomaly to shortcomings of the long range bond order potential (LCBOP) employed in the nanoindentation study. read less NOT USED (high confidence) A. Aghajamali, C. de Tomas, I. Suarez-Martinez, and N. Marks, “Unphysical nucleation of diamond in the extended cutoff Tersoff potential,” Molecular Simulation. 2018. link Times cited: 8 Abstract: In simulations of carbon materials it is common practice to … read moreAbstract: In simulations of carbon materials it is common practice to view the coefficients of the cutoff function as free parameters which can be optimised according to the system of interest. This work examines a common modification to the widely used Tersoff potential in which the coefficient of the upper cutoff is increased to improve the properties of amorphous carbon. Using molecular dynamics simulations, we show that this so-called extended cutoff Tersoff model leads to nucleation of diamond nanocrystals during annealing of amorphous carbon. By varying the density of the system, and examining the radial distribution function in conjunction with the modified cutoff function, we demonstrate that this behaviour is unphysical, and does not represent a new pathway for synthesising diamond. Viewed from a broader perspective, this observation provides a cautionary tale against altering the parameters of empirical potentials without fully considering the wider implications. read less NOT USED (high confidence) F. Gargiulo and O. Yazyev, “Structural and electronic transformation in low-angle twisted bilayer graphene,” 2D Materials. 2017. link Times cited: 120 Abstract: Experiments on bilayer graphene unveiled a fascinating reali… read moreAbstract: Experiments on bilayer graphene unveiled a fascinating realization of stacking disorder where triangular domains with well-defined Bernal stacking are delimited by a hexagonal network of strain solitons. Here we show by means of numerical simulations that this is a consequence of a structural transformation of the moiré pattern inherent to twisted bilayer graphene taking place at twist angles θ below a crossover angle θ⋆=1.2∘. The transformation is governed by the interplay between the interlayer van der Waals interaction and the in-plane strain field, and is revealed by a change in the functional form of the twist energy density. This transformation unveils an electronic regime characteristic of vanishing twist angles in which the charge density converges, though not uniformly, to that of ideal bilayer graphene with Bernal stacking. On the other hand, the stacking domain boundaries form a distinct charge density pattern that provides the STM signature of the hexagonal solitonic network. read less NOT USED (high confidence) R. Lindsey, L. Fried, and N. Goldman, “ChIMES: A Force Matched Potential with Explicit Three-Body Interactions for Molten Carbon.,” Journal of chemical theory and computation. 2017. link Times cited: 50 Abstract: We present a new force field and development scheme for atom… read moreAbstract: We present a new force field and development scheme for atomistic simulations of materials under extreme conditions. These models, which explicitly include two- and three-body interactions, are generated by fitting linear combinations of Chebyshev polynomials through force matching to trajectories from Kohn-Sham density functional theory (DFT). We apply our method to liquid carbon near the diamond/graphite/liquid triple point and at higher densities and temperatures, where metallization and many-body effects may be substantial. We show that explicit inclusion of three-body interaction terms allows our model to yield improved descriptions of both dynamic and structural properties over previous empirical potential efforts, while exhibiting transferability to nearby state points. The simplicity of our functional form and subsequent efficiency of parameter determination allow for extension of DFT to experimental time and length scales while retaining most of its accuracy. read less NOT USED (high confidence) T. Maaravi, I. Leven, I. Azuri, L. Kronik, and O. Hod, “Interlayer Potential for Homogeneous Graphene and Hexagonal Boron Nitride Systems: Reparametrization for Many-Body Dispersion Effects,” Journal of Physical Chemistry C. 2017. link Times cited: 55 Abstract: A new parametrization of the anisotropic interlayer potentia… read moreAbstract: A new parametrization of the anisotropic interlayer potential for hexagonal boron nitride (h-BN ILP) is presented. The force-field is benchmarked against density functional theory calculations of several dimer systems within the Heyd-Scuseria-Ernzerhof hybrid density functional approximation, corrected for many-body dispersion effects. The latter, more advanced method for treating dispersion, is known to produce binding energies nearly twice as small as those obtained with pairwise correction schemes, used for an earlier ILP parametrization. The new parametrization yields good agreement with the reference calculations to within ∼1 and ∼0.5 meV/atom for binding and sliding energies, respectively. For completeness, we present a complementary parameter set for homogeneous graphitic systems. Together with our previously suggested ILP parametrization for the heterogeneous graphene/h-BN junction, this provides a powerful tool for consistent simulation of the structural, mechanical, tribological, and heat transp... read less NOT USED (high confidence) G. D. Chatzidakis, G. Kalosakas, Z. Fthenakis, and N. Lathiotakis, “A torsional potential for graphene derived from fitting to DFT results,” The European Physical Journal B. 2017. link Times cited: 5 NOT USED (high confidence) V. Zalizniak and O. A. Zolotov, “Efficient embedded atom method interatomic potential for graphite and carbon nanostructures,” Molecular Simulation. 2017. link Times cited: 5 Abstract: A new interatomic potential for graphite and graphene based … read moreAbstract: A new interatomic potential for graphite and graphene based on embedded atom method is proposed in this paper. Potential parameters were determined by fitting to the equilibrium lattice constants, the binding energy, the vacancy formation energy and elastic constants. The agreement between the calculated properties of graphite and experimental data is very good. In addition, the proposed potential quite accurately reproduces the surface energy of graphite and the binding energies of carbon atom in fullerene C60 and in SWNTs. The proposed potential is computationally more efficient than the existing widely used carbon potentials. It is intended for use in large-scale molecular dynamics simulations of carbon structures. read less NOT USED (high confidence) N. Tsujimoto, D. Adachi, R. Akashi, S. Todo, and S. Tsuneyuki, “Crystal Structure Prediction Supported by Incomplete Experimental Data,” arXiv: Materials Science. 2017. link Times cited: 5 Abstract: The prediction of material structure from chemical compositi… read moreAbstract: The prediction of material structure from chemical composition has been a long-standing challenge in natural science. Although there have been various methodological developments and successes with computer simulations, the prediction of crystal structures comprising more than several tens of atoms in the unit cell still remains difficult due to the many degrees of freedom, which increase exponentially with the number of atoms. Here we show that when some experimental data is available, even if it is totally insufficient for conventional structure analysis, it can be utilized to support and substantially accelerate structure simulation. In particular, we formulate a cost function based on a weighted sum of interatomic potential energies and a penalty function referred to as "crystallinity", which is defined using limited X-ray diffraction data. This method is applied to well-known polymorphs of $\rm{SiO_2}$ with up to 96 atoms in the simulation cell to find that it reproduces the correct structures efficiently with a very limited number of diffraction peaks. The penalty function is confirmed to destabilize the local minima of the potential energy surface, which facilitates finding the correct structure. This method opens a new avenue for determining and predicting structures that are difficult to determine by conventional methods, such as surface, interface, glass, and amorphous structures. read less NOT USED (high confidence) S. Schweizer et al., “Molecular Modeling of Microporous Structures of Carbide-Derived Carbon-Based Supercapacitors,” Journal of Physical Chemistry C. 2017. link Times cited: 18 Abstract: Microporous carbide-derived carbons are an important structu… read moreAbstract: Microporous carbide-derived carbons are an important structural class for various technological applications. We present two possible strategies based on molecular dynamics simulations for modeling microporous amorphous carbon. In addition, we have investigated the influence of the precursor structure and simulation parameters on the porosity of the final model structure. We observed a minor influence of the precursor structure on the porosity and found that the structural properties such as pore size and hybridization in the modeled carbon structures agree well with experimental findings. Moreover, CO2 adsorption isotherms have been simulated using Monte Carlo simulations for comparsion with experimental data. In this context, we have also considered partially oxidized carbon structures for which an increased uptake of CO2 was observed. read less NOT USED (high confidence) C. Herrero and R. Ramírez, “Quantum effects in graphene monolayers: Path-integral simulations.,” The Journal of chemical physics. 2016. link Times cited: 28 Abstract: Path-integral molecular dynamics (PIMD) simulations have bee… read moreAbstract: Path-integral molecular dynamics (PIMD) simulations have been carried out to study the influence of quantum dynamics of carbon atoms on the properties of a single graphene layer. Finite-temperature properties were analyzed in the range from 12 to 2000 K, by using the LCBOPII effective potential. To assess the magnitude of quantum effects in structural and thermodynamic properties of graphene, classical molecular dynamics simulations have been also performed. Particular emphasis has been laid on the atomic vibrations along the out-of-plane direction. Even though quantum effects are present in these vibrational modes, we show that at any finite temperature classical-like motion dominates over quantum delocalization, provided that the system size is large enough. Vibrational modes display an appreciable anharmonicity, as derived from a comparison between kinetic and potential energies of the carbon atoms. Nuclear quantum effects are found to be appreciable in the interatomic distance and layer area at finite temperatures. The thermal expansion coefficient resulting from PIMD simulations vanishes in the zero-temperature limit, in agreement with the third law of thermodynamics. read less NOT USED (high confidence) C. Tomas, I. Suarez-Martinez, and N. Marks, “Graphitization of amorphous carbons: A comparative study of interatomic potentials,” Carbon. 2016. link Times cited: 160 NOT USED (high confidence) M. Dharma-wardana, “Theory of complex fluids in the warm dense matter regime and application to an unusual phase transition in liquid carbon,” Contributions to Plasma Physics. 2016. link Times cited: 8 Abstract: Data from recent laser‐shock experiments or from simulations… read moreAbstract: Data from recent laser‐shock experiments or from simulations using density functional theory (DFT), molecular dynamics (MD), path integrals etc. that are available for warm dense carbon are compared with the corresponding results predicted using the neutral pseudo‐atom [NPA] method. The NPA results are in good agreement not only with the 3–12 g/cm3 regimes that have been studied via path‐integral Monte Carlo methods but even at low densities and low temperatures where transient covalent bonding dominates ionic correlations. Thus, the “prepeak” due to the C–C bond at ∼1.4 Å and other features found in the pair distribution function g[r] from DFT + MD simulations at 0.86 eV and 3.7 g/cm3 and other densities etc. are recovered accurately in the NPA + HNC (hypernetted‐chain) calculations. The exploration of regimes not covered by previous studies is presented together with evidence of an unusual phase transition of carbon in the liquid state to a vapour, as seen from the loss of ion–ion correlations. An abrupt decrease in the number of free electrons per ion occurs simultaneously. A metallic liquid with strong ionic correlations arising from transient C–C bonds becomes a metallic vapour. This occurs when carbon at the density of ∼1.0 g/cm3 and mean ionization Z = 4 transits abruptly to a disordered mono‐atomic vapour at 7 eV, with Z ≃ 3. The behaviour of the pressure, compressibility and the electrical conductivity as well as physical quantities available from X‐ray Thomson scattering are presented across the tentatively proposed phase transition. read less NOT USED (high confidence) V. Hizhnyakov, A. Shelkan, M. Haas, and M. Klopov, “Discrete breathers above phonon spectrum,” Letters on Materials. 2016. link Times cited: 13 Abstract: It is shown that in some metals (Ni, Nb, Fe, Cu) may exist d… read moreAbstract: It is shown that in some metals (Ni, Nb, Fe, Cu) may exist discrete breathers with frequencies above the top of the phonon spectrum. These excitations are mobile: they may propagate along the crystallographic directions transferring energy of > ~ 1 eV over large distances. The discrete breathers with the frequencies above the top of the phonon bands may also exist in covalent crystals (diamond, Si and Ge). It is also found that in monatomic chains and planes (e.g. in graphene), the transverse discrete breathers may be excited above the spectrum of corresponding phonons. Although these vibrations are in resonance with longitudinal (chain) or in-plane (graphene) phonons the lifetime of them may be very long. read less NOT USED (high confidence) R. Nicholl et al., “The effect of intrinsic crumpling on the mechanics of free-standing graphene,” Nature Communications. 2015. link Times cited: 207 NOT USED (high confidence) X. W. Zhou, D. Ward, and M. E. Foster, “An analytical bond‐order potential for carbon,” Journal of Computational Chemistry. 2015. link Times cited: 38 Abstract: Carbon is the most widely studied material today because it … read moreAbstract: Carbon is the most widely studied material today because it exhibits special properties not seen in any other materials when in nano dimensions such as nanotube and graphene. Reduction of material defects created during synthesis has become critical to realize the full potential of carbon structures. Molecular dynamics (MD) simulations, in principle, allow defect formation mechanisms to be studied with high fidelity, and can, therefore, help guide experiments for defect reduction. Such MD simulations must satisfy a set of stringent requirements. First, they must employ an interatomic potential formalism that is transferable to a variety of carbon structures. Second, the potential needs to be appropriately parameterized to capture the property trends of important carbon structures, in particular, diamond, graphite, graphene, and nanotubes. Most importantly, the potential must predict the crystalline growth of the correct phases during direct MD simulations of synthesis to achieve a predictive simulation of defect formation. Because an unlimited number of structures not included in the potential parameterization are encountered, the literature carbon potentials are often not sufficient for growth simulations. We have developed an analytical bond order potential for carbon, and have made it available through the public MD simulation package LAMMPS. We demonstrate that our potential reasonably captures the property trends of important carbon phases. Stringent MD simulations convincingly show that our potential accounts not only for the crystalline growth of graphene, graphite, and carbon nanotubes but also for the transformation of graphite to diamond at high pressure. © 2015 Wiley Periodicals, Inc. read less NOT USED (high confidence) R. Elder, M. Neupane, and T. Chantawansri, “Stacking order dependent mechanical properties of graphene/MoS2 bilayer and trilayer heterostructures,” Applied Physics Letters. 2015. link Times cited: 41 Abstract: Transition metal dichalcogenides (TMDC) such as molybdenum d… read moreAbstract: Transition metal dichalcogenides (TMDC) such as molybdenum disulfide (MoS2) are two-dimensional materials that show promise for flexible electronics and piezoelectric applications, but their weak mechanical strength is a barrier to practical use. In this work, we perform nanoindentation simulations using atomistic molecular dynamics to study the mechanical properties of heterostructures formed by combining MoS2 with graphene. We consider both bi- and tri-layer heterostructures formed with MoS2 either supported or encapsulated by graphene. Mechanical properties, such as Young's modulus, bending modulus, ultimate tensile strength, and fracture strain, are extracted from nanoindentation simulations and compared to the monolayer and homogeneous bilayer systems. We observed that the heterostructures, regardless of the stacking order, are mechanically more robust than the mono- and bi-layer MoS2, mainly due to the mechanical reinforcement provided by the graphene layer. The magnitudes of ultimate strength and f... read less NOT USED (high confidence) M. Migliorato et al., “Beyond ZnO nanowires for piezotronics and nanogenerators,” 2015 IEEE 15th International Conference on Nanotechnology (IEEE-NANO). 2015. link Times cited: 0 Abstract: In the past decade ZnO nanowires have been the key enabling … read moreAbstract: In the past decade ZnO nanowires have been the key enabling material for demonstrating novel electronics components in the field of piezotronics and in the first realization of a nanogenerator. What are the materials that will be crucial in demonstrating even more novel devices in future years? We propose the use of both core shell nanowires and graphene as key enablers of new functionalities. read less NOT USED (high confidence) A. Fraile, E. Koukaras, K. Papagelis, N. Lazarides, and G. P. Tsironis, “Long-lived discrete breathers in free-standing graphene,” Chaos Solitons & Fractals. 2015. link Times cited: 20 NOT USED (high confidence) J. Kroes, F. Pietrucci, A. V. van Duin, and W. Andreoni, “Atom Vacancies on a Carbon Nanotube: To What Extent Can We Simulate their Effects?,” Journal of chemical theory and computation. 2015. link Times cited: 7 Abstract: Atom vacancies are intrinsic defects of carbon nanotubes. Us… read moreAbstract: Atom vacancies are intrinsic defects of carbon nanotubes. Using a zigzag nanotube as reference, this paper focuses on the comparison of calculations performed within density functional theory and a number of classical force fields widely used for carbon systems. The results refer to single and double vacancies and, in particular, to the induced structural changes, the formation energies, and the energy barriers relative to elementary processes such as reconstruction, migration, and coalescence. Characterization of these processes is remarkably different in the different approaches. These findings are meant to contribute to the construction of DFT-based classical schemes for carbon nanostructures. read less NOT USED (high confidence) N. Orekhov and V. Stegailov, “Graphite melting: Atomistic kinetics bridges theory and experiment,” Carbon. 2015. link Times cited: 38 NOT USED (high confidence) H. Whitley, D. M. Sanchez, S. Hamel, A. Correa, and L. Benedict, “Molecular Dynamics Simulations of Warm Dense Carbon,” Contributions to Plasma Physics. 2015. link Times cited: 10 Abstract: We present classical and DFT‐based molecular dynamics (MD) s… read moreAbstract: We present classical and DFT‐based molecular dynamics (MD) simulations of carbon in the warm dense matter regime (ϱ = 3.7 g/cc, 0.86 eV < T < 8.62 eV [T < 100 eV for classical MD]). Two different classical interatomic potentials are used: 1. LCBOP, designed to simulate condensed (e.g. solid) phases of C, and 2. linearly screened Coulomb (Yukawa) potentials. It is shown that LCBOP over‐predicts minima and maxima in the pair correlation functions of liquid‐C in this regime when compared to the DFT‐MD results. The screened Coulomb model, while under‐correlating at low‐T, seems to produce the correct qualitative features in the static ionic pair distributions at the highest‐T. However, both approaches predict the decay in the ionic contribution of the specific heat as T → ∞ to be much slower than that predicted by a model based on DFT‐MD. These differences in the MD‐derived equations of state in warm dense regimes could have important consequences when using classical inter‐ionic forces such as these in large‐scale MD simulations aimed at studying, for instance, processes of relevance to inertial confinement fusion when C is used as an ablator material. (© 2015 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) read less NOT USED (high confidence) P. Süle and M. Szendrő, “Time-lapsed graphene moiré superlattices on Cu(1 1 1),” Modelling and Simulation in Materials Science and Engineering. 2015. link Times cited: 7 Abstract: We report classical molecular dynamics simulations (CMD) of … read moreAbstract: We report classical molecular dynamics simulations (CMD) of the moiré superlattice of graphene on Cu(1 1 1) using a new parameterized Abell–Tersoff potential for the graphene/Cu(1 1 1) interface fitted in this paper to nonlocal van der Waals density functional theory calculations. The interfacial force field with time-lapsed CMD provides superlattices in good quantitative agreement with the available experimental results. The long range coincidence supercells with nonequivalent moiré hills have also been identified and analyzed. Spot profile analysis reveals that the moiré spots are inequivalent over large areas, and their heights are randomly distributed. This result is in accordance with recent atomic force microscopy studies. Our simulations also shed light on the transient dynamics of the moiré superlattice in atomic detail. The moiré superlattice exhibits a pattern which is dynamical rather than statically pinned to the support, and can be observed mostly via time-lapsing. The instantaneous snapshots of the periodic moiré pattern at low temperature are already weakly disordered, lacking the apparent sharpness of the time-averaged pattern and of the scanning tunneling microscopy images. This suggests the existence of competition of orders—between a static (first-order) moiré superstructure and a dynamical (second-order) moiré superstructure. read less NOT USED (high confidence) Y. Magnin, G. D. Förster, F. Rabilloud, F. Calvo, A. Zappelli, and C. Bichara, “Thermal expansion of free-standing graphene: benchmarking semi-empirical potentials,” Journal of Physics: Condensed Matter. 2014. link Times cited: 55 Abstract: The thermodynamical properties of free-standing graphene hav… read moreAbstract: The thermodynamical properties of free-standing graphene have been investigated under constant zero pressure as a function of temperature using Monte Carlo simulations. A variety of atomistic models have been used, including the simple three-body Stillinger potential and a series of bond-order many-body potentials based on the Tersoff–Brenner seminal models, with recent reparametrizations dedicated to graphene, extensions to medium-range or long-range dispersion corrections. In addition, we have also tested a tight-binding potential in the fourth-moment approximation. The simulations reveal significant discrepancies in the in-plane lattice parameter and the thermal expansion coefficient, which despite showing monotonically increasing variations with temperature, can be positive, negative or change sign at moderate temperature depending on the potential. Comparison with existing experimental and theoretical data obtained from complementary approaches indicates that empirical potentials limited to nearest-neighbour interactions give rather dispersed results, and that van der Waals corrections generally tend to flatten the variations of the in-plane lattice constant, in contradiction with experiment. Only the medium-range corrected potentials of Los and Fasolino, as well as the tight-binding model in the fourth-moment approximation, are reasonably close to the reference results near room temperature. Our results suggest that classical potentials should be used with caution for thermal properties. read less NOT USED (high confidence) N. Orekhov and V. Stegailov, “Molecular dynamics simulation of graphite melting,” High Temperature. 2014. link Times cited: 20 NOT USED (high confidence) J.-M. Leyssale and G. Vignoles, “A Large-Scale Molecular Dynamics Study of the Divacancy Defect in Graphene,” Journal of Physical Chemistry C. 2014. link Times cited: 39 Abstract: We report on the dynamical behavior of single divacancy defe… read moreAbstract: We report on the dynamical behavior of single divacancy defects in large graphene sheets as studied by extensive classical molecular dynamics (MD) simulations at high temperatures and static calculations. In the first part of the paper, the ability of the used interatomic potential to properly render the stability and dynamics (energy barriers) of such defects is validated against electronic structure calculations from the literature. Then, results from MD simulations are presented. In agreement with recent TEM studies, some mobility is observed through a series of Stone–Wales-like bond rotations involving the 5–8–5, 555–777, and 5555–6–7777 reconstructions. Although these three structures are by far the most probable structures of the DV defect, not less than 18 other full reconstructions, including the experimentally observed 55–66–77 defect, were occasionally observed in the ≈1.5 μs of MD trajectories analyzed in this work. Most of these additional reconstructions have moderate formation energies and c... read less NOT USED (high confidence) K. Chae, Y. Shi, and L. Huang, “Nanocasting of hierarchical nanostructured porous carbon in molecular dynamics simulation,” Journal of Materials Chemistry. 2013. link Times cited: 14 Abstract: We developed a model template method mimicking the nanocasti… read moreAbstract: We developed a model template method mimicking the nanocasting process by introducing cylindrical templates during the quenched molecular dynamics process [Y. Shi, J. Chem. Phys., 2008, 128, 234707] to generate hierarchical nanostructured porous carbons (HNPCs). Bimodal pore size distributions with both mesopores (from templates) and micropores (from the direct quenching of the carbon source) were well developed during the mimetic nanocasting process. The structure and properties of the nanocast HNPCs can be tailored by various control parameters, such as the template–carbon interaction strength (et), the template radius (rt), the number density of the carbon source (ρ0) and the quench rate (qr). The mesopore wall is made of graphitic carbons, whose morphology can be well-controlled by et and high temperature heat treatments, while the microporous structure can be engineered by ρ0 and qr. The crystallinity of the mesopore wall and the structural integrity of HNPCs (characterized by the number of bridging bonds between the mesopore wall and the microporous region) can be balanced by fine-tuning the control parameters. The mimetic nanocasting method allows us to generate atomic models to quantify the relationship between the structure and properties of HNPCs, and to provide guidelines for identifying the optimal synthesis parameters for HNPCs with desired properties. read less NOT USED (high confidence) E. Baĭtinger, E. A. Belenkov, M. Brzhezinskaya, and V. Greshnyakov, “Specific features of the structure of detonation nanodiamonds from results of electron microscopy investigations,” Physics of the Solid State. 2012. link Times cited: 22 NOT USED (high confidence) Y. Choi, S. Mahalingam, and A. Likhanskii, “Predicting Hall thruster operational lifetime with computational models,” 2012 IEEE Aerospace Conference. 2012. link Times cited: 2 Abstract: A combination of the use of a kinetic plasma code and a mole… read moreAbstract: A combination of the use of a kinetic plasma code and a molecular dynamics simulation method is presented for Hall thruster channel wall erosion modeling over time. The kinetic plasma model simulates the thruster channel plasma of an SPT-100 thruster to calculate the ion flux to the walls. The molecular dynamics model simulates the sputtering of boron nitride to calculate sputter yields. A comparison of sample erosion profiles with experimental data is performed. read less NOT USED (high confidence) P. Ganesh, P. Kent, and V. Mochalin, “Formation, characterization, and dynamics of onion-like carbon structures for electrical energy storage from nanodiamonds using reactive force fields,” Journal of Applied Physics. 2011. link Times cited: 55 Abstract: We simulate the experimentally observed graphitization of na… read moreAbstract: We simulate the experimentally observed graphitization of nanodiamonds into multi-shell onion-like carbon nanostructures, also called carbon onions, at different temperatures, using reactive force fields. The simulations include long-range Coulomb and van der Waals interactions. Our results suggest that long-range interactions play a crucial role in the phase-stability and the graphitization process. Graphitization is both enthalpically and entropically driven and can hence be controlled with temperature. The outer layers of the nanodiamond have a lower kinetic barrier toward graphitization irrespective of the size of the nanodiamond and graphitize within a few-hundred picoseconds, with a large volume increase. The inner core of the nanodiamonds displays a large size-dependent kinetic barrier, and graphitizes much more slowly with abrupt jumps in the internal energy. It eventually graphitizes by releasing pressure and expands once the outer shells have graphitized. The degree of transformation at a partic... read less NOT USED (high confidence) L. Karssemeijer and A. Fasolino, “Phonons of graphene and graphitic materials derived from the empirical potential LCBOPII,” Surface Science. 2010. link Times cited: 100 NOT USED (high confidence) A. S. de Wijn, C. Fusco, and A. Fasolino, “Stability of superlubric sliding on graphite.,” Physical review. E, Statistical, nonlinear, and soft matter physics. 2010. link Times cited: 46 Abstract: Recent atomic force microscope (AFM) experiments have shown … read moreAbstract: Recent atomic force microscope (AFM) experiments have shown that the low-friction sliding of incommensurate graphite flakes on graphite can be destroyed by torque-induced rotations. Here we theoretically investigate the stability of superlubric sliding against rotations of the flake. We find that the occurrence of superlubric motion critically depends on the physical parameters and on the experimental conditions: particular scan lines, thermal fluctuations, and high loading forces can destroy the stability of superlubric orbits. We find that the optimal conditions to achieve superlubric sliding are given by large flakes, low temperature, and low loads, as well as scanning velocities higher than those used in AFM experiments. read less NOT USED (high confidence) S. Okada, Y. Takagi, and T. Kawai, “Formation of Multi-Walled Nanotubes from Diamond Nanowires,” Japanese Journal of Applied Physics. 2010. link Times cited: 1 Abstract: Based on classical molecular dynamics simulation, we show th… read moreAbstract: Based on classical molecular dynamics simulation, we show the possibility of the formation of multi-walled carbon nanotubes from diamond nanowires at elevated temperatures. Since the outermost shell of a diamond nanowire can be regarded as a corrugated graphene sheet bound via elongated intershell bonds, thermal annealing of the nanowire causes successive peeling of the outermost shell and results in a structural transformation from an sp3 structure into an sp2 rich nanostructure. The resultant structures could be classified as multi-walled carbon nanotubes with some stacking faults. read less NOT USED (high confidence) Y. Xiao, W. Dong, and H. F. Busnengo, “Reactive force fields for surface chemical reactions: A case study with hydrogen dissociation on Pd surfaces.,” The Journal of chemical physics. 2010. link Times cited: 35 Abstract: An approach based on reactive force fields is applied to the… read moreAbstract: An approach based on reactive force fields is applied to the parametrization of potential energy surface (PES) for chemical reactions on surfaces with a benchmark system, H(2)/Pd(111). We show that a simple reactive force field based on the second moment approximation does not allow for obtaining reliable results of reaction dynamics for the considered system. With a more elaborate reactive force field, i.e., reactive bond order (REBO) force field, we succeeded in obtaining a reliable PES for H(2)/Pd(111). The accuracy of the constructed REBO force field is carefully checked through various tests including the comparison not only between energies calculated with density functional theory and those with REBO force field but also between the available results of ab initio molecular dynamics simulations and those with our force field. Moreover, our REBO force field is endowed with some transferability since the force field constructed with a database containing only information on H(2)/Pd(111) allows for obtaining also accurate results for H(2)/Pd(100) and qualitatively correct results for H(2)/Pd(110) without any refitting. With the help of our reactive force field, the molecular dynamics simulation for the dissociation of H(2) on the considered Pd surfaces is speeded up by five orders of magnitude compared to ab initio molecular dynamics method. The demonstrated reliability and the very high computational efficiency of reactive force fields open extremely attractive perspectives for studying large-scale complex reacting systems. read less NOT USED (high confidence) M. Rapacioli et al., “Correction for dispersion and Coulombic interactions in molecular clusters with density functional derived methods: application to polycyclic aromatic hydrocarbon clusters.,” The Journal of chemical physics. 2009. link Times cited: 81 Abstract: The density functional based tight binding (DFTB) is a semie… read moreAbstract: The density functional based tight binding (DFTB) is a semiempirical method derived from the density functional theory (DFT). It inherits therefore its problems in treating van der Waals clusters. A major error comes from dispersion forces, which are poorly described by commonly used DFT functionals, but which can be accounted for by an a posteriori treatment DFT-D. This correction is used for DFTB. The self-consistent charge (SCC) DFTB is built on Mulliken charges which are known to give a poor representation of Coulombic intermolecular potential. We propose to calculate this potential using the class IV/charge model 3 definition of atomic charges. The self-consistent calculation of these charges is introduced in the SCC procedure and corresponding nuclear forces are derived. Benzene dimer is then studied as a benchmark system with this corrected DFTB (c-DFTB-D) method, but also, for comparison, with the DFT-D. Both methods give similar results and are in agreement with references calculations (CCSD(T) and symmetry adapted perturbation theory) calculations. As a first application, pyrene dimer is studied with the c-DFTB-D and DFT-D methods. For coronene clusters, only the c-DFTB-D approach is used, which finds the sandwich configurations to be more stable than the T-shaped ones. read less NOT USED (high confidence) Y. Shi, “A mimetic porous carbon model by quench molecular dynamics simulation.,” The Journal of chemical physics. 2008. link Times cited: 65 Abstract: A mimetic porous carbon model is generated using quench mole… read moreAbstract: A mimetic porous carbon model is generated using quench molecular dynamics simulations that reproduces experimental radial distribution functions of activated carbon. The resulting structure is composed of curved and defected graphene sheets. The curvature is induced by nonhexagonal rings. The quench conditions are systematically varied and the final porous structure is scrutinized in terms of its pore size distribution, pore connectivity, and fractal dimension. It is found that the initial carbon density affects the fractal dimension but only causes a minor shift in the pore size distribution. On the other hand, the quench rate affects the pore size distribution but only causes a minor shift in the fractal dimension. read less NOT USED (high confidence) L. Ghiringhelli, C. Valeriani, J. H. Los, E. Meijer, A. Fasolino, and D. Frenkel, “State-of-the-art models for the phase diagram of carbon and diamond nucleation,” Molecular Physics. 2008. link Times cited: 52 Abstract: We review recent developments in the modelling of the phase … read moreAbstract: We review recent developments in the modelling of the phase diagram and the kinetics of crystallization of carbon. In particular, we show that a particular class of bond-order potentials (the so-called LCBOP models) account well for many of the known structural and thermodynamic properties of carbon at high pressures and temperatures. We discuss the LCBOP models in some detail. In addition, we briefly review the ‘history’ of experimental and theoretical studies of the phase behaviour of carbon. Using a well-tested version of the LCBOP model (viz. LCBOPI+) we address some of the more controversial hypotheses concerning the phase behaviour of carbon, in particular: the suggestion that liquid carbon can exist in two phases separated by a first-order phase transition and the conjecture that diamonds could have formed by homogeneous nucleation in Uranus and Neptune. read less NOT USED (high confidence) T. X. Nguyen, S. Bhatia, S. Jain, and K. Gubbins, “Structure of saccharose-based carbon and transport of confined fluids: hybrid reverse Monte Carlo reconstruction and simulation studies,” Molecular Simulation. 2006. link Times cited: 43 Abstract: We present results of the reconstruction of a saccharose-bas… read moreAbstract: We present results of the reconstruction of a saccharose-based activated carbon (CS1000a) using hybrid reverse Monte Carlo (HRMC) simulation, recently proposed by Opletal et al. [1]. Interaction between carbon atoms in the simulation is modeled by an environment dependent interaction potential (EDIP) [2,3]. The reconstructed structure shows predominance of sp2 over sp3 bonding, while a significant proportion of sp hybrid bonding is also observed. We also calculated a ring distribution and geometrical pore size distribution of the model developed. The latter is compared with that obtained from argon adsorption at 87 K using our recently proposed characterization procedure [4], the finite wall thickness (FWT) model. Further, we determine self-diffusivities of argon and nitrogen in the constructed carbon as functions of loading. It is found that while there is a maximum in the diffusivity with respect to loading, as previously observed by Pikunic et al. [5], diffusivities in the present work are 10 times larger than those obtained in the prior work, consistent with the larger pore size as well as higher porosity of the activated saccharose carbon studied here. read less NOT USED (high confidence) L. Ghiringhelli, J. Los, E. Meijer, A. Fasolino, and D. Frenkel, “Liquid carbon: structure near the freezing line,” Journal of Physics: Condensed Matter. 2005. link Times cited: 13 Abstract: We present a detailed analysis of the structure of liquid ca… read moreAbstract: We present a detailed analysis of the structure of liquid carbon near the freezing line. The results are obtained by molecular simulation using a recently developed state-of-the-art bond order potential. We find that along the melting line the liquid is predominantly threefold coordinated up to pressures far beyond the liquid–graphite–diamond triple point. We find no sign of a first-order liquid–liquid phase transition when, at 10 500 K and ∼300 GPa, the local structure of the liquid along the melting line changes dominant coordination from three- to fourfold. read less NOT USED (high confidence) L. Ghiringhelli, J. Los, E. Meijer, A. Fasolino, and D. Frenkel, “High-pressure diamondlike liquid carbon,” Physical Review B. 2004. link Times cited: 30 Abstract: We report density-functional based molecular-dynamics simula… read moreAbstract: We report density-functional based molecular-dynamics simulations, which show that, with increasing pressure, liquid carbon undergoes a gradual transformation from a liquid with local threefold coordination to a "diamondlike" liquid. We demonstrate that this unusual structural change is well reproduced by an empirical bond-order potential with isotropic long-range interactions, supplemented by torsional terms. In contrast, state-of-the-art short-range bond-order potentials do not reproduce this diamond structure. This suggests that a correct description of long-range interactions is crucial for a unified description of the solid and liquid phases of carbon. read less NOT USED (high confidence) C. Fusco and A. Fasolino, “Power-law load dependence of atomic friction,” Applied Physics Letters. 2004. link Times cited: 14 Abstract: We present a theoretical study of the dynamics of a tip scan… read moreAbstract: We present a theoretical study of the dynamics of a tip scanning a graphite surface as a function of the applied load. From the analysis of the lateral forces, we extract the friction force and the corrugation of the effective tip-surface interaction potential. We find both the friction force and potential amplitude to have a power-law dependence on applied load with exponent ∼1.6. We interpret these results as characteristic of sharp undeformable tips in contrast to the case of macroscopic and elastic microscopic contacts. read less NOT USED (definite) R. Jana, D. Savio, V. L. Deringer, and L. Pastewka, “Structural and elastic properties of amorphous carbon from simulated quenching at low rates,” Modelling and Simulation in Materials Science and Engineering. 2019. link Times cited: 22 Abstract: We generate representative structural models of amorphous ca… read moreAbstract: We generate representative structural models of amorphous carbon (a-C) from constant-volume quenching from the liquid with subsequent relaxation of internal stresses in molecular dynamics simulations using empirical and machine-learning interatomic potentials. By varying volume and quench rate we generate structures with a range of density and amorphous morphologies. We find that all a-C samples show a universal relationship between hybridization, bulk modulus and density despite having distinctly different cohesive energies. Differences in cohesive energy are traced back to slight changes in the distribution of bond-angles that is likely linked to thermal stability of these structures. read less NOT USED (definite) U. Monteverde et al., “Under pressure: control of strain, phonons and bandgap opening in rippled graphene,” Carbon. 2015. link Times cited: 59 |
