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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.
182 Citations (118 used)
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USED (definite) T. Cea, N. Walet, and F. Guinea, “Twists and the electronic structure of graphitic materials.,” Nano letters. 2019. link Times cited: 51 Abstract: We analyze the effect of twists on the electronic structure … read moreAbstract: We analyze the effect of twists on the electronic structure of configurations of infinite stacks of graphene layers. We focus on three different cases: an infinite stack where each layer is rotated with respect to the previous one by a fixed angle, two pieces of semi-infinite graphite rotated with respect to each other, and finally a single layer of graphene rotated with respect to a graphite surface. In all three cases we find a rich structure, with sharp resonances and flat bands for small twist angles. The method used can be easily generalized to more complex arrangements and stacking sequences. read less USED (definite) F. Guinea and N. Walet, “Continuum models for twisted bilayer graphene: Effect of lattice deformation and hopping parameters,” Physical Review B. 2019. link Times cited: 91 Abstract: We analyze a description of twisted graphene bilayers, that … read moreAbstract: We analyze a description of twisted graphene bilayers, that incorporates deformation of the layers due to the nature modern interlayer potentials, and a modification of the hopping parameters between layers in the light of the classic Slonczewski-Weiss-McClure parametrisation. We shall show that flat bands result in all cases, but that their nature can be rather different. We will show how to construct a more general reduction to a continuum model, and show that even though such a model can be constructed, its complexity increases, requiring more coupling parameters to be included, and the full in-layer dispersion to be taken into account. We conclude that the combination of all these effects will have a large impact on the wave functions of the flat bands, and that changes in the detail of the underlying models can lead to significant changes. A robust conclusion is that the natural strength of the interlayer couplings is higher than usually assumed, which causes additional Dirac points to appear for the standard magic angles. This gives rise to a degeneracy at the $\Gamma$ point. Since the appearance of a gap at the $\Gamma$ point is crucial for the construction of the Wannier states which are used in the standard descriptions of superconductivity, such an approach not be robust. read less USED (definite) M. A. G. Cunha and M. Robbins, “Determination of pressure-viscosity relation of 2,2,4-trimethylhexane by all-atom molecular dynamics simulations,” Fluid Phase Equilibria. 2019. link Times cited: 15 USED (definite) H. Wang, Q. Cao, Q. Peng, and S. Liu, “Atomistic Study of Mechanical Behaviors of Carbon Honeycombs,” Nanomaterials. 2019. link Times cited: 13 Abstract: With an ultralarge surface-to-volume ratio, a recently synth… read moreAbstract: With an ultralarge surface-to-volume ratio, a recently synthesized three-dimensional graphene structure, namely, carbon honeycomb, promises important engineering applications. Herein, we have investigated, via molecular dynamics simulations, its mechanical properties, which are inevitable for its integrity and desirable for any feasible implementations. The uniaxial tension and nanoindentation behaviors are numerically examined. Stress–strain curves manifest a transformation of covalent bonds of hinge atoms when they are stretched in the channel direction. The load–displacement curve in nanoindentation simulation implies the hardness and Young’s modulus to be 50.9 GPa and 461±9 GPa, respectively. Our results might be useful for material and device design for carbon honeycomb-based systems. read less USED (definite) V. Jadhao and M. Robbins, “Probing large viscosities in glass-formers with nonequilibrium simulations,” Proceedings of the National Academy of Sciences. 2017. link Times cited: 56 Abstract: Significance As a liquid cools, molecules move more slowly a… read moreAbstract: Significance As a liquid cools, molecules move more slowly and the viscosity rises. A fundamental question is whether this trend continues smoothly down to zero temperature, or if flow stops at a finite temperature where the material undergoes a transition to a glass phase. Direct measurements of growing viscosities become difficult as the time for motion exceeds years or centuries. We describe and test an approach for obtaining large viscosities using nonequilibrium molecular dynamics simulations. Results agree with existing experiments on the model glass-former squalane and allow viscosities over 10 orders of magnitude larger to be predicted. The temperature dependence at fixed pressure or density is consistent with a gradual slowing of dynamics, rather than a finite-temperature divergence in viscosity. For decades, scientists have debated whether supercooled liquids stop flowing below a glass transition temperature Tg0 or whether motion continues to slow gradually down to zero temperature. Answering this question is challenging because human time scales set a limit on the largest measurable viscosity, and available data are equally well fit to models with opposite conclusions. Here, we use short simulations to determine the nonequilibrium shear response of a typical glass-former, squalane. Fits of the data to an Eyring model allow us to extrapolate predictions for the equilibrium Newtonian viscosity ηN over a range of pressures and temperatures that change ηN by 25 orders of magnitude. The results agree with the unusually large set of equilibrium and nonequilibrium experiments on squalane and extend them to higher ηN. Studies at different pressures and temperatures are inconsistent with a diverging viscosity at finite temperature. At all pressures, the predicted viscosity becomes Arrhenius with a single temperature-independent activation barrier at low temperatures and high viscosities (ηN>103 Pa⋅s). Possible experimental tests of our results are outlined. read less USED (definite) R. Mirzayev et al., “Buckyball sandwiches,” Science Advances. 2017. link Times cited: 43 Abstract: A two-dimensional petri dish of fullerenes in a graphene wra… read moreAbstract: A two-dimensional petri dish of fullerenes in a graphene wrap allows electron microscopy observation of atomic-scale dynamics. Two-dimensional (2D) materials have considerably expanded the field of materials science in the past decade. Even more recently, various 2D materials have been assembled into vertical van der Waals heterostacks, and it has been proposed to combine them with other low-dimensional structures to create new materials with hybridized properties. We demonstrate the first direct images of a suspended 0D/2D heterostructure that incorporates C60 molecules between two graphene layers in a buckyball sandwich structure. We find clean and ordered C60 islands with thicknesses down to one molecule, shielded by the graphene layers from the microscope vacuum and partially protected from radiation damage during scanning transmission electron microscopy imaging. The sandwich structure serves as a 2D nanoscale reaction chamber, allowing the analysis of the structure of the molecules and their dynamics at atomic resolution. read less USED (definite) J. Ewen, C. Gattinoni, F. Thakkar, N. Morgan, H. Spikes, and D. Dini, “Nonequilibrium Molecular Dynamics Investigation of the Reduction in Friction and Wear by Carbon Nanoparticles Between Iron Surfaces,” Tribology Letters. 2016. link Times cited: 46 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) Z. Luo, S. A. Burrows, X. Fan, S. Smoukov, and E. Boek, “Virtual voids method to generate low-density microporous carbon structures using quenched molecular dynamics simulation,” Carbon. 2021. link Times cited: 1 USED (high confidence) X. Xiao, S. Fan, C. Li, and Y. Liu, “Optical-Thermally Excited Graphene Resonant Mass Detection: A Molecular Dynamics Analysis,” Nanomaterials. 2021. link Times cited: 2 Abstract: In consideration of the presented optical-thermally excited … read moreAbstract: In consideration of the presented optical-thermally excited resonant mass detection scheme, molecular dynamics calculations are performed to investigate the thermal actuation and resonant mass sensing mechanism. The simulation results indicate that an extremely high temperature exists in a 6% central area of the graphene sheet exposed to the exciting laser. Therefore, constraining the laser driving power and enlarging the laser spot radius are essential to weaken the overheating in the middle of the graphene sheet, thus avoiding being burned through. Moreover, molecular dynamics calculations demonstrate a mass sensitivity of 214 kHz/zg for the graphene resonator with a pre-stress of 1 GPa. However, the adsorbed mass would degrade the resonant quality factor from 236 to 193. In comparison, the sensitivity and quality factor could rise by 1.3 and 4 times, respectively, for the graphene sheet with a pre-stress of 5 GPa, thus revealing the availability of enlarging pre-stress for better mass sensing performance. read less USED (high confidence) M. He, K. L. Joshi, and L. Zhigilei, “Computational study of the effect of core–skin structure on the mechanical properties of carbon nanofibers,” Journal of Materials Science. 2021. link Times cited: 6 USED (high confidence) A. Fischer, Z. A. H. Goodwin, A. Mostofi, J. Lischner, D. Kennes, and L. Klebl, “Unconventional superconductivity in magic-angle twisted trilayer graphene,” npj Quantum Materials. 2021. link Times cited: 38 USED (high confidence) C. Brand et al., “The morphology of doubly-clamped graphene nanoribbons,” 2D Materials. 2021. link Times cited: 1 Abstract: Understanding the response of micro/nano-patterned graphene … read moreAbstract: Understanding the response of micro/nano-patterned graphene to mechanical forces is instrumental for applications such as advanced graphene origami and kirigami. Here, we analyze free-standing nanoribbons milled into single-layer graphene by focused ion beam processing. Using transmission electron microscopy, we show that the length L of the structures determines their morphology. Nanoribbons with L below 300 nm remain mainly flat, whereas longer ribbons exhibit uni-axial crumpling or spontaneous scrolling, a trend that is well reproduced by molecular dynamics simulations. We measure the strain of the ribbons as well as their crystallinity by recording nanometer-resolved convergent beam electron diffraction maps, and show that the beam tails of the focused ion beam cause significant amorphization of the structures adjacent to the cuts. The expansive or compressive strain in the structures remains below 4%. Our measurements provide experimental constraints for the stability of free-standing graphene structures with respect to their geometry, providing guidelines for future applications of patterned graphene. read less USED (high confidence) X. Xiao, S. Fan, and C. Li, “The Effect of Edge Mode on Mass Sensing for Strained Graphene Resonators,” Micromachines. 2021. link Times cited: 7 Abstract: Edge mode could disturb the ultra-subtle mass detection for … read moreAbstract: Edge mode could disturb the ultra-subtle mass detection for graphene resonators. Herein, classical molecular dynamics simulations are performed to investigate the effect of edge mode on mass sensing for a doubly clamped strained graphene resonator. Compared with the fundamental mode, the localized vibration of edge mode shows a lower frequency with a constant frequency gap of 32.6 GHz, despite the mutable inner stress ranging from 10 to 50 GPa. Furthermore, the resonant frequency of edge mode is found to be insensitive to centrally located adsorbed mass, while the frequency of the fundamental mode decreases linearly with increasing adsorbates. Thus, a mass determination method using the difference of these two modes is proposed to reduce interferences for robust mass measurement. Moreover, molecular dynamics simulations demonstrate that a stronger prestress or a higher width–length ratio of about 0.8 could increase the low-quality factor induced by edge mode, thus improving the performance in mass sensing for graphene resonators. read less USED (high confidence) J. Li, R. Long, B. Zhang, R. Yang, W. Liu, and Z. Liu, “Nano Heat Pump Based on Reverse Thermo-Osmosis Effect.,” The journal of physical chemistry letters. 2020. link Times cited: 7 Abstract: Heat pumps are widely used in domesticity, agriculture, and … read moreAbstract: Heat pumps are widely used in domesticity, agriculture, and industry. Here, we report a novel heat pump based on reverse thermo-osmosis (RTO) effect in a nanoporous graphene (NPG) membrane. Through classical molecular dynamics (MD) simulation, we prove that the heat pump can transport mass and heat efficiently. The heat and mass fluxes are increased linearly with the hydraulic pressure provided. Ultra-high heat fluxes of 6.2±1.0 kW/cm2 and coefficient of performance (COP) of 20.2 are obtained with a temperature increment of 5 K and a working pressure of 80 MPa. It is interesting that water molecules on the NPG membrane can evaporate in a cluster state and the cluster evaporations reduce the vaporization enthalpy of the processes. read less USED (high confidence) X. Liang, Z. A. H. Goodwin, V. Vitale, F. Corsetti, A. Mostofi, and J. Lischner, “Effect of bilayer stacking on the atomic and electronic structure of twisted double bilayer graphene,” Physical Review B. 2020. link Times cited: 12 Abstract: Twisted double bilayer graphene has recently emerged as an i… read moreAbstract: Twisted double bilayer graphene has recently emerged as an interesting moire material that exhibits strong correlation phenomena that are tunable by an applied electric field. Here, we study the atomic and electronic properties of three different graphene double bilayers: double bilayers composed of two AB stacked bilayers (AB/AB), double bilayers composed of two AA stacked bilayers (AA/AA) as well as heterosystems composed of one AB and one AA bilayer (AB/AA). First, the atomic structure is determined using classical force fields. We find that the inner layers of the double bilayer exhibit significant in-plane and out-of-plane relaxations, similar to twisted bilayer graphene. The relaxations of the outer layers depend on the stacking: outer-layer atoms in AB bilayers follow the relaxations of the inner layers, while outer-layer atoms in AA bilayers attempt to avoid higher-energy AA stacking. For the relaxed structures, we calculate the electronic band structures using the tight-binding method. All double bilayers exhibit flat bands at small twist angles, but the shape of the bands depends sensitively on the stacking of the outer layers. To gain further insight, we study the evolution of the band structure as the outer layers are rigidly moved away from the inner layers, while preserving their atomic relaxations. This reveals that the hybridization with the outer layers results in an additional flattening of the inner-layer flat band manifold. Our results establish AA/AA and AB/AA twisted double bilayers as interesting moire materials with different flat band physics compared to the widely studied AB/AB system. read less USED (high confidence) X. Zhou, H. Cai, C. Hu, J. Shi, Z. Li, and K. Cai, “Analogous Diamondene Nanotube Structure Prediction Based on Molecular Dynamics and First-Principle Calculations,” Nanomaterials. 2020. link Times cited: 4 Abstract: A concentric twin tube (CTT) can be built by placing a carbo… read moreAbstract: A concentric twin tube (CTT) can be built by placing a carbon nanotube (CNT) in another identical CNT. Different from diamondene nanotubes, a stable CTT has no inter-shell covalent bond. As a prestressed double-walled nanotube, CTT has a lower structural stability at a finite temperature. According to the molecular dynamics and first-principle calculations, (a) CTTs have three types of relaxed configurations. In a type III CTT, the inner tube buckles to produce a V-shaped cross-section, and the outer tube may be convex or concave. (b) The minimal radii of relaxed zigzag and armchair CTTs with concave outer tubes were found. (c) After relaxation, the circumferences and areas of the two tubes in a type III CTT are different from those of the corresponding ideal CNT. The area change rate (A-CR) and circumference change rate (C-CR) of the outer tube are the first-order Gaussian function of the radius of the ideal CNT (which forms the CTT), and tends to be 73.3% of A-CR or 95.3% of C-CR, respectively. For the inner tube of a CTT, the A-CR is between 29.3% and 37.0%, and the C-CR is close to 95.8%. (d) The temperature slightly influences the findings given above. read less USED (high confidence) M. Shishehbor and M. Pouranian, “Tuning the Mechanical and Adhesion Properties of Carbon Nanotubes Using Aligned Cellulose Wrap (Cellulose Nanotube): A Molecular Dynamics Study,” Nanomaterials. 2020. link Times cited: 11 Abstract: Improving the adhesion properties of carbon nanotubes (CNTs)… read moreAbstract: Improving the adhesion properties of carbon nanotubes (CNTs) at the molecular scale can significantly enhance dispersion of CNT fibers in polymer matrix and unleash the dormant extraordinary mechanical properties of CNTs in CNT-polymer nanocomposites. Inspired by the outstanding adhesion, dispersion, mechanical, and surface functionalization properties of crystalline nanocellulose (CNC), this paper studies the mechanical and adhesion properties of CNT wrapped by aligned cellulose chains around CNT using molecular dynamic simulations. The strength, elastic modulus, and toughness of CNT-cellulose fiber for different cellulose contents are obtained from tensile and compression tests. Additionally, the effect of adding cellulose on the surface energy, interfacial shear modulus, and strength is evaluated. The result shows that even adding a single layer cellulose wrap (≈55% content) significantly decreases the mechanical properties, however, it also dramatically enhances the adhesion energy, interfacial shear strength, and modulus. Adding more cellulose layers, subsequently, deceases and increases mechanical properties and adhesion properties, respectively. In addition, analysis of nanopapers of pristine CNT, pristine CNC, and CNT-wrapped cellulose reveals that CNT-wrapped cellulose nanopapers are strong, stiff, and tough, while for CNT and CNC either strength or toughness is compromised. This research shows that cellulose wraps provide CNT fibers with tunable mechanical properties and adhesion energy that could yield strong and tough materials due to the excellent mechanical properties of CNT and active surface and hydrogen bonding of cellulose. read less USED (high confidence) K. L. Joshi, M. I. Arefev, and L. Zhigilei, “Generation and characterization of carbon fiber microstructures by atomistic simulations,” Carbon. 2019. link Times cited: 41 USED (high confidence) J. Zhu et al., “Unveiling carbon ring structure formation mechanisms in polyacrylonitrile-derived carbon fibers.,” ACS applied materials & interfaces. 2019. link Times cited: 31 Abstract: As the demand for electric vehicles (EVs) and autonomous veh… read moreAbstract: As the demand for electric vehicles (EVs) and autonomous vehicles (AVs) rapidly grows, lower-cost, lighter, and stronger carbon fibers (CFs) are urgently needed to respond to consumers' call for greater EV traveling range and stronger safety structures for AVs. Converting polymeric precursors to CFs requires a complex set of thermochemical processes; a systematic understanding of each parameter in fiber conversion is still, to a large extent, lacking. Here we demonstrate the effect of carbonization temperature on carbon ring structure formation by combining atomistic/microscale simulations and experimental validation. Experimental testing, as predicted by simulations, exhibited that the strength and ductility of PAN CFs decreased whereas the Young's modulus increased with increasing carbonization temperature. Our simulations unveiled that high carbonization temperature accelerated the kinetics of graphitic phase nucleation and growth, leading to the decrease in strength and ductility but increase in modulus. The methodology presented herein using combined atomistic/microscale simulations and experimental validation lays a firm foundation for further innovation in CF manufacturing and low-cost alternative precursor development. read less USED (high confidence) L. Pascazio, J. W. Martin, M. L. Botero, M. Sirignano, A. D’Anna, and M. Kraft, “Mechanical Properties of Soot Particles: The Impact of Crosslinked Polycyclic Aromatic Hydrocarbons,” Combustion Science and Technology. 2019. link Times cited: 15 Abstract: ABSTRACT In this paper, we estimate the degree of crosslinki… read moreAbstract: ABSTRACT In this paper, we estimate the degree of crosslinking within soot particles making use of reactive molecular dynamics simulations of mechanical properties of crosslinked polycyclic aromatic hydrocarbons (PAH). Representative systems of PAH (pyrene, coronene, ovalene and circumpyrene) with a density similar to soot and with varying degrees of crosslinking were built. Uniaxial tensile test simulations were carried out on the systems and the yield stress of each sample was calculated. The hardness was estimated from the yield stress using an empirical conversion constant and the obtained values were compared with nanoindentation experiments of soot particles. The results show that mature ethylene and diesel soot particles are expected to present a degree of crosslinking between 2.1–3.0 and 3.0–3.5, respectively, to have a value comparable to the hardness found experimentally. Finally, an MD simulation of nanoindentation of a particle of crosslinked coronene molecules provided an alternative means to compute the empirical constant used to convert the yield stress in hardness. These results reveal the importance of crosslinking reactions during soot maturation that give rise to a structure in which the majority of aromatics are aliphatically linked in a 3D network. read less USED (high confidence) I.-C. Yeh and J. Andzelm, “Calculations of free energy of surface interactions in crystalline polyethylene.,” The Journal of chemical physics. 2018. link Times cited: 6 Abstract: The surface free energy of the crystalline polyethylene (PE)… read moreAbstract: The surface free energy of the crystalline polyethylene (PE) is an important property related with wettability, adhesion, and crystal growth. We investigated the profiles of free energy of surface interactions in the fully thermalized crystalline PE during debonding and shearing with atomistic molecular dynamics simulations using steered molecular dynamics and umbrella sampling techniques. The stress profiles during debonding and shearing processes were also estimated and compared with those obtained from analogous deformation simulations. We estimated the vacuum surface free energies of two different crystallographic surfaces (100) and (010) of the crystalline PE from the free energy changes during the debonding process. The estimated surface free energies were insensitive to the choice of simulation protocols after combining estimates from both forward and backward processes and were in excellent agreement with those obtained from an experiment on PE single crystal aggregates, which underscores the importance of the inclusion of the entropic contribution in the free energy calculated with the fully flexible interface adopted in this study. read less USED (high confidence) M. Slepchenkov, P. Barkov, and O. Glukhova, “High-Density Hydrogen Storage in a 2D-Matrix from Graphene Nanoblisters: A Prospective Nanomaterial for Environmentally Friendly Technologies.” 2018. link Times cited: 4 Abstract: In this paper, the atomic structure and mechanical stability… read moreAbstract: In this paper, the atomic structure and mechanical stability of a new structural graphene modification—a 2D matrix of nanoscale cells in the form of a few-layer graphene substrate and nanoblister of a graphene monolayer—were studied for the first time. It is shown that such matrices are mechanically stable and are promising for environmentally friendly technologies. The calculated local atomic stress fields demonstrate that the atomic framework is not destroyed, even in the presence of defects in the atomic network of graphene nanoblister (Stone-Wales defect, double vacancies defect, ad-dimmer defect, and their combination). However, it was established that the presence of one or more SW defects leads to the appearance of critical stresses. These critical stresses can induce local bond breaking in the atomic network with an increase in temperature or external pressure. It was found that graphene nanoblister can store molecular hydrogen with a maximum density of 6.6 wt % for 1158 m2/g at 77 K under normal pressure. read less USED (high confidence) R. Li, W. Gong, Q. He, Q. Li, W. Lu, and W. Zhu, “Joining cross-stacked carbon nanotube architecture with covalent bonding,” Applied Physics Letters. 2017. link Times cited: 3 Abstract: Carbon nanotubes (CNTs) have superior mechanical properties … read moreAbstract: Carbon nanotubes (CNTs) have superior mechanical properties that make them highly attractive for high performance bulk structures such as CNT fibers and films; however, the weak wan der Waals interaction between CNTs gives degraded strength and modulus, forming covalent bonding between CNTs which is considered to be highly promising but remains a considerable challenge due to the inert nature of the carbon surface. An appropriate electron-beam, as yet, has been used to introduce covalent bonding but limited to CNT bundles. Here, we used a spinnable CNT array to form a cross-stacked CNT architecture first, a bulk film, and proved that sp3 covalent bonding can be directly formed between cross-stacked CNTs under high pressure at appropriate temperatures via a laser heated diamond anvil cell method. The Raman spectrum and molecular dynamic simulations were used to probe and interpret the bonding formation process, respectively. It was found that under 30 GPa with the temperature of 765–1345 K, sp3 covalent bo... read less USED (high confidence) I.-C. Yeh, J. L. Lenhart, G. Rutledge, and J. Andzelm, “Molecular Dynamics Simulation of the Effects of Layer Thickness and Chain Tilt on Tensile Deformation Mechanisms of Semicrystalline Polyethylene,” Macromolecules. 2017. link Times cited: 52 Abstract: We performed molecular dynamics simulations to investigate t… read moreAbstract: We performed molecular dynamics simulations to investigate the effects of layer thicknesses of both crystalline and noncrystalline domains and chain tilt within the crystalline lamellae on tensile deformation mechanisms of the lamellar stack model of semicrystalline polyethylene. For equal thicknesses of crystalline and noncrystalline regions, similar stress–strain profiles were obtained with two different initial orientations of the crystal stem relative to the tensile direction. Repeated melting/recrystallization transitions were observed, at the slower strain rate of 5 × 106 s–1, characterized by oscillating stress–strain profiles. With increasing thickness of the crystalline regions, these oscillations occurred less frequently. For systems with initially tilted chain stems in the crystalline domain, decreasing the thickness of the noncrystalline region increased the number of short bridge segments in the noncrystalline region connecting the two crystalline regions and induced significant shear stresse... read less USED (high confidence) S. Ozden et al., “Ballistic Fracturing of Carbon Nanotubes.,” ACS applied materials & interfaces. 2016. link Times cited: 16 Abstract: Advanced materials with multifunctional capabilities and hig… read moreAbstract: Advanced materials with multifunctional capabilities and high resistance to hypervelocity impact are of great interest to the designers of aerospace structures. Carbon nanotubes (CNTs) with their lightweight and high strength properties are alternative to metals and/or metallic alloys conventionally used in aerospace applications. Here we report a detailed study on the ballistic fracturing of CNTs for different velocity ranges. Our results show that the highly energetic impacts cause bond breakage and carbon atom rehybridizations, and sometimes extensive structural reconstructions were also observed. Experimental observations show the formation of nanoribbons, nanodiamonds, and covalently interconnected nanostructures, depending on impact conditions. Fully atomistic reactive molecular dynamics simulations were also carried out in order to gain further insights into the mechanism behind the transformation of CNTs. The simulations show that the velocity and relative orientation of the multiple colliding nanotubes are critical to determine the impact outcome. read less USED (high confidence) Y. Timoshina, E. Voznesensky, A. E. Karnoukhov, V. Zheltukhin, and A. I. Teptina, “Simulation of the processes of plasma modification and vacuum metallization of polymer materials by the method of molecular dynamics,” E3S Web of Conferences. 2023. link Times cited: 0 Abstract: The article presents the results of the development of molec… read moreAbstract: The article presents the results of the development of molecular dynamics models of modifications of polypropylene (PP) material in the plasma of a radio-frequency (RF) discharge and a copper coating deposit by magnetron sputtering on the surface of a polyethylene (PE) material. The model of the RF plasma modification process describes changes in the surface layers of the PP material upon interaction with low-energy plasma ions: the nature of the breaking of covalent bonds in macromolecules, the chemical composition of sputtered particles, and changes in the ordering of the supramolecular structure. The model of the vacuum metallization process describes the processes of the introduction of metal atoms into the polymer structure, the change in the conformation of macromolecules, the formation of macroradicals with uncompensated chemical bonds, and the formation of an interfacial layer between the polymer and the metal coating. read less USED (high confidence) Ł. Radosiński, R. Havryliv, and P. Żemojtel, “Molecular dynamics simulation of Ion Beam Etching as technology process for creating graphene-based membranes,” Chemical technology and engineering. Proceedings.2019.№1. 2019. link Times cited: 0 Abstract: – Carbon nanomaterials present new possibilities for creatin… read moreAbstract: – Carbon nanomaterials present new possibilities for creating permeable membranes. Ionic beam etching technology allows to create pores in graphene substrates and has the potential to be used in various separation processes. In our study we present a molecular dynamics simulation of the energy needed to puncture the graphene surface to create porous surface. Experimental part shows dependency of irradiation time to pore diameter on silica substrate, which indicates it is possible to create pore diameters lesser than the beam diameter. We present a technology process of creating pores of a specific diameter. read less USED (low confidence) W. Yang et al., “Effect of hydrogen concentration on the friction evolution mechanism of few-layer graphene: A molecular dynamics study in nanoscratch processes,” Surface Science. 2024. link Times cited: 0 USED (low confidence) Z. Tang, J. Zhao, and Y. Wang, “Molecular study on convective heat transfer of nanofluid in nanochannel: effect of CNT particles,” Journal of Thermal Analysis and Calorimetry. 2023. link Times cited: 0 USED (low confidence) B. Goh, C.-L. Park, S. H. Kim, and J. Choi, “Structural criticality manifested by a polarized ionic layer on a MWCNT yarn surface under mechanical loading,” Carbon. 2023. link Times cited: 0 USED (low confidence) J. Baimova and S. A. Shcherbinin, “Strength and Deformation Behavior of Graphene Aerogel of Different Morphologies,” Materials. 2023. link Times cited: 0 Abstract: Graphene aerogels are of high interest nowadays since they h… read moreAbstract: Graphene aerogels are of high interest nowadays since they have ultralow density, rich porosity, high deformability, and good adsorption. In the present work, three different morphologies of graphene aerogels with a honeycomb-like structure are considered. The strength and deformation behavior of these graphene honeycomb structures are studied by molecular dynamics simulation. The effect of structural morphology on the stability of graphene aerogel is discussed. It is shown that structural changes significantly depend on the structural morphology and the loading direction. The deformation of the re-entrant honeycomb is similar to the deformation of a conventional honeycomb due to the opening of the honeycomb cells. At the first deformation stage, no stress increase is observed due to the structural transformation. Further, stress concentration on the junctions of the honeycomb structure and over the walls occurs. The addition of carbon nanotubes and graphene flakes into the cells of graphene aerogel does not result in a strength increase. The mechanisms of weakening are analyzed in detail. The obtained results further contribute to the understanding of the microscopic deformation mechanisms of graphene aerogels and their design for various applications. read less USED (low confidence) J. P. Mikhail and G. C. Rutledge, “Mechanisms of Shock Dissipation in Semicrystalline Polyethylene,” Polymers. 2023. link Times cited: 0 Abstract: Semicrystalline polymers are lightweight, multiphase materia… read moreAbstract: Semicrystalline polymers are lightweight, multiphase materials that exhibit attractive shock dissipation characteristics and have potential applications as protective armor for people and equipment. For shocks of 10 GPa or less, we analyzed various mechanisms for the storage and dissipation of shock wave energy in a realistic, united atom (UA) model of semicrystalline polyethylene. Systems characterized by different levels of crystallinity were simulated using equilibrium molecular dynamics with a Hugoniostat to ensure that the resulting states conform to the Rankine–Hugoniot conditions. To determine the role of structural rearrangements, order parameters and configuration time series were collected during the course of the shock simulations. We conclude that the major mechanisms responsible for the storage and dissipation of shock energy in semicrystalline polyethylene are those associated with plastic deformation and melting of the crystalline domain. For this UA model, plastic deformation occurs primarily through fine crystallographic slip and the formation of kink bands, whose long period decreases with increasing shock pressure. read less USED (low confidence) T. Panczyk and K. Nieszporek, “Formation of degraded LDPE surfaces using mechanical cleavage and shock compression analyzed by means of molecular dynamics simulations,” Computational Materials Science. 2023. link Times cited: 0 USED (low confidence) Y. Li and B. Zhang, “Structural transition of single-walled carbon nanotube (6, 6) bundles under lateral shocks,” Diamond and Related Materials. 2023. link Times cited: 0 USED (low confidence) A. B. A. Tahhan, M. Alkhedher, A. Mourad, M. Ramadan, and M. Shehadeh, “Molecular Dynamics study on buckling behavior of vertically aligned carbon nanotube (VACNT) bundles with characterized waviness,” Computational Materials Science. 2023. link Times cited: 1 USED (low confidence) A. Jimeno-Pozo et al., “Short Versus Long Range Exchange Interactions in Twisted Bilayer Graphene,” Advanced Physics Research. 2023. link Times cited: 0 Abstract: This study discusses the effect of long‐range interactions w… read moreAbstract: This study discusses the effect of long‐range interactions within the self‐consistent Hartree‐Fock (HF) approximation in comparison to short‐range atomic Hubbard interactions on the band structure of twisted bilayer graphene (TBG) at charge neutrality for various twist angles. Starting from atomistic calculations, it determines the quasi‐particle band structure of TBG with Hubbard interactions for three magnetic orderings: modulated anti‐ferromagnetic (MAFM), (NAFM) and hexagonal anti‐ferromagnetic (HAFM). Then, it develops an approach to incorporate these magnetic orderings along with the HF potential in the continuum approximation. Away from the magic angle, it observes a drastic effect of the magnetic order on the band structure of TBG compared to the influence of the HF potential. Near the magic angle, the HF potential plays a major role in the band structure, with HAFM and MAFM being secondary effects, but NAFM appears to still significantly distort the electronic structure at the magic angle. These findings suggest that the spin‐valley degenerate broken symmetry state often found in HF calculations of charge neutral TBG near the magic angle should favor magnetic order, since the atomistic Hubbard interaction will break this symmetry in favor of spin polarization. read less USED (low confidence) G. C. Otakandza‐Kandjani, P. Brault, M. Mikikian, A. Michau, and K. Hassouni, “Molecular dynamics approach for the calculation of the surface loss probabilities of neutral species in argon–methane plasma,” Plasma Processes and Polymers. 2023. link Times cited: 0 Abstract: Molecular dynamics simulations are carried out for calculati… read moreAbstract: Molecular dynamics simulations are carried out for calculating the surface loss probabilities of neutral species from an argon–methane plasma. These probabilities are the sum of the sticking and surface recombination probabilities. This study considers both the formation of reactive and nonreactive volatile species for evaluating recombination probabilities. Results show that stable species are reflected when hydrocarbon film starts growing on the surface. CH3 is mainly lost by surface recombination leading to the formation of volatile products while very little contributes to film growth. C2H has surface loss probability in agreement with the literature. While C2H loss is usually attributed to sticking on the surface, our results show that its main loss process is due to surface recombination. read less USED (low confidence) P. Babaev et al., “Atomic-scale insights into damage produced by swift heavy ions in polyethylene,” Journal of Materials Science. 2023. link Times cited: 0 USED (low confidence) L. V. Bastos, R. S. Ambekar, C. Tiwary, D. Galvão, and C. Woellner, “Mechanical energy absorption of architecturally interlocked petal-schwarzites,” Carbon Trends. 2023. link Times cited: 0 USED (low confidence) A. Sharma, S. Sharma, and S. Ajori, “Molecular dynamics simulation of the mechanical and thermal properties of phagraphene nanosheets and nanotubes: a review,” Journal of Materials Science. 2023. link Times cited: 0 USED (low confidence) B. Goh and J. Choi, “Nonlinear multiscale model for interstitial structures of densely ordered multi-walled carbon nanotube bundles,” Carbon. 2023. link Times cited: 1 USED (low confidence) D. Rapp, S. Hocker, H. Lipp, and S. Schmauder, “Strengthening and failure of iron-graphene composites: A molecular dynamics study,” Computational Materials Science. 2023. link Times cited: 1 USED (low confidence) M. Curatolo and G. Salerno, “Holes interaction of a graphene membrane under pressure for water desalination,” Mechanics of Materials. 2023. link Times cited: 0 USED (low confidence) S. R. Maalouf and S. Vel, “Nonlinear elastic behavior of 2D materials using molecular statics and comparisons with first principles calculations,” Physica E: Low-dimensional Systems and Nanostructures. 2023. link Times cited: 2 USED (low confidence) K. Čerņevičs, M. Fuechsle, M. Broome, M. Choucair, and O. Yazyev, “Origin of metallic-like behavior in disordered carbon nano-onions,” Carbon. 2023. link Times cited: 0 USED (low confidence) S. Chowdhury, T. Longoria, and J. Gillespie, “Effects of transverse compression on the structure and axial tensile properties of polyethylene: A molecular simulation study,” Polymer. 2023. link Times cited: 2 USED (low confidence) X. Zhu et al., “Effect of the Graphitization Mechanism on the Friction and Wear Behavior of DLC Films Based on Molecular Dynamics Simulations.,” Langmuir : the ACS journal of surfaces and colloids. 2023. link Times cited: 6 Abstract: Whether a graphitization mechanism can control the low-frict… read moreAbstract: Whether a graphitization mechanism can control the low-friction behavior of DLC films is still controversial. In this paper, we establish the molecular dynamics model of the DLC film with graphene (DLC-GR-DLC) by LAMMPS and study the influence of the graphitization mechanism on the friction and wear behavior of the DLC film. The friction force of the DLC-GR-DLC model in the running-in stage is significantly smaller than that of the DLC film and then gradually increases to the same size as that of the DLC film. Further analysis indicates that the graphitization mechanism could indeed reduce the shear stress of the friction interface when graphene remains intact. However, the curling and breaking of the graphene structure will lead to an increase in shear force at the friction interface. read less USED (low confidence) O. Dyck et al., “Top‐Down Fabrication of Atomic Patterns in Twisted Bilayer Graphene,” Advanced Materials. 2023. link Times cited: 3 Abstract: Atomic‐scale engineering typically involves bottom‐up approa… read moreAbstract: Atomic‐scale engineering typically involves bottom‐up approaches, leveraging parameters such as temperature, partial pressures, and chemical affinity to promote spontaneous arrangement of atoms. These parameters are applied globally, resulting in atomic‐scale features scattered probabilistically throughout the material. In a top‐down approach, different regions of the material are exposed to different parameters, resulting in structural changes varying on the scale of the resolution. In this work, the application of global and local parameters is combined in an aberration‐corrected scanning transmission electron microscope (STEM) to demonstrate atomic‐scale precision patterning of atoms in twisted bilayer graphene. The focused electron beam is used to define attachment points for foreign atoms through the controlled ejection of carbon atoms from the graphene lattice. The sample environment is staged with nearby source materials such that the sample temperature can induce migration of the source atoms across the sample surface. Under these conditions, the electron‐beam (top‐down) enables carbon atoms in the graphene to be replaced spontaneously by diffusing adatoms (bottom‐up). Using image‐based feedback control, arbitrary patterns of atoms and atom clusters are attached to the twisted bilayer graphene with limited human interaction. The role of substrate temperature on adatom and vacancy diffusion is explored by first‐principles simulations. read less USED (low confidence) K. K. Gupta, T. Mukhopadhyay, and S. Dey, “Probing the molecular-level energy absorption mechanism and strategic sequencing of graphene/Al composite laminates under high-velocity ballistic impact of nano-projectiles,” Applied Surface Science. 2023. link Times cited: 3 USED (low confidence) G. O. Kandjani, P. Brault, M. Mikikian, G. Tetard, A. Michau, and K. Hassouni, “Molecular dynamics simulations of reactive neutral chemistry in an argon‐methane plasma,” Plasma Processes and Polymers. 2022. link Times cited: 2 USED (low confidence) H.-N. Zhang, Y. Fan, and H. S. Shen, “Chirality-Dependent and Intrinsic Auxeticity for Single-Walled Carbon Nanotubes,” Materials. 2022. link Times cited: 2 Abstract: Single-walled carbon nanotubes (SWCNTs) have superior mechan… read moreAbstract: Single-walled carbon nanotubes (SWCNTs) have superior mechanical properties which originate from a strong C-C covalent bond and unique nanostructure. Chirality, one of the helical structural parameters of SWCNTs, leads to differences in mechanical performance. In this work, molecular dynamics (MD) simulation was performed to analyze engineering Poisson’s ratio (EPR) and incremental Poisson’s ratio (IPR) of SWCNTs with different chiral angles, respectively, under tensile and compressive load, as well as the chiral effect on rigidity. We reported the minimum EPR for (4, 1) SWCNT and obtained the distribution and trend of EPR which is dependent on chiral index m. In addition, a new observation showed two exactly opposite trends of EPR existing not only in tension and compression but also in the longitudinal and radial directions. Furthermore, we found that the critical strain, over which SWCNT would be auxetic, ranged from 6% to 18% and was also chirality-dependent. Three representative SWCNTs with chiral angle of 0° (zigzag), 10.89° (chiral), and 30° (armchair) were selected for the mechanism study of auxeticity. Finally, a method of the contribution to radial strain for two main deformation modes proposed in this paper could well explain the negative IPR phenomenon. read less USED (low confidence) M. He, M. I. Arefev, K. L. Joshi, and L. Zhigilei, “Atomistic Modeling of Tensile Deformation and Fracture of Carbon Fibers: Nanoscales Stress Redistribution, Effect of Local Structural Characteristics and Nanovoids,” SSRN Electronic Journal. 2022. link Times cited: 1 USED (low confidence) J. R. Gissinger et al., “Predicting char yield of high-temperature resins,” Carbon. 2022. link Times cited: 3 USED (low 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 USED (low confidence) A. Schuster et al., “Recovery of release cloud from laser shock-loaded graphite and hydrocarbon targets: in search of diamonds,” Journal of Physics D: Applied Physics. 2022. link Times cited: 3 Abstract: This work presents first insights into the dynamics of free-… read moreAbstract: This work presents first insights into the dynamics of free-surface release clouds from dynamically compressed polystyrene and pyrolytic graphite at pressures up to 200 GPa, where they transform into diamond or lonsdaleite, respectively. These ejecta clouds are released into either vacuum or various types of catcher systems, and are monitored with high-speed recordings (frame rates up to 10 MHz). Molecular dynamics simulations are used to give insights to the rate of diamond preservation throughout the free expansion and the catcher impact process, highlighting the challenges of diamond retrieval. Raman spectroscopy data show graphitic signatures on a catcher plate confirming that the shock-compressed PS is transformed. First electron microscopy analyses of solid catcher plates yield an outstanding number of different spherical-like objects in the size range between ten(s) up to hundreds of nanometres, which are one type of two potential diamond candidates identified. The origin of some objects can unambiguously be assigned, while the history of others remains speculative. read less USED (low confidence) J. Zhao et al., “Molecular dynamics simulation of H2 in amorphous polyethylene system: H2 diffusion in various PE matrices and bubbling during rapid depressurization,” International Journal of Hydrogen Energy. 2022. link Times cited: 4 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) J. Chen and W. Ge, “Computational study on the order-of-magnitude difference in thermal conductivity between graphene and graphane nanoribbons,” Diamond and Related Materials. 2022. link Times cited: 1 USED (low confidence) O. Dyck, S. Yeom, S. Dillender, A. Lupini, M. Yoon, and S. Jesse, “The role of temperature on defect diffusion and nanoscale patterning in graphene,” Carbon. 2022. link Times cited: 9 USED (low confidence) V. Kushch, “A Study of Thermodynamic and Elastic Properties of Nanosized Diamond Single Crystals by the Classical Molecular Dynamics Method,” Journal of Superhard Materials. 2022. link Times cited: 2 USED (low confidence) K. K. Gupta, A. Roy, T. Mukhopadhyay, L. Roy, and S. Dey, “Probing the stochastic fracture behavior of twisted bilayer graphene: Efficient ANN based molecular dynamics simulations for complete probabilistic characterization,” Materials Today Communications. 2022. link Times cited: 10 USED (low confidence) S. Attarian and S. Xiao, “Investigating the strength of Ti/TiB interfaces at multiple scales using density functional theory, molecular dynamics, and cohesive zone modeling,” Ceramics International. 2022. link Times cited: 1 USED (low confidence) L. Zhang and H. Ban, “Thermal Energy Transfer between Helium Gas and Graphene Surface According to Molecular Dynamics Simulations and the Monte Carlo Method,” Nanomaterials. 2022. link Times cited: 0 Abstract: The scattering of gases on solid surfaces plays a vital role… read moreAbstract: The scattering of gases on solid surfaces plays a vital role in many advanced technologies. In this study, the scattering behavior of helium on graphene surfaces was investigated, including the thermal accommodation coefficient (TAC), outgoing zenith angle of helium, bounce number, and interaction time. First, we performed molecular dynamics simulations to describe the incident angle-resolved behaviors, and showed that the scattering is highly dependent on the zenith angle of incident helium but insensitive to the azimuthal angle. The contribution of the normal velocity component of the incident helium dominated the energy transfer. The nonlinear relationship of the parameters to the zenith angle of the incident helium could be suppressed by increasing the graphene temperature or decreasing the speed of the incident helium. Subsequently, the scattering performance considering all gas molecules in the hemispherical space was evaluated using the Monte Carlo method with angle-resolved results. The result showed that the TAC, its nominal components, and the zenith angle of the scattered helium increased with higher speeds of incident helium and lower temperatures of graphene. This study should provide a fundamental understanding of energy transfer between gas and two-dimensional materials and guidelines to tune the scattering behavior between them. read less USED (low confidence) M. A. Torkaman-Asadi and M. A. Kouchakzadeh, “Atomistic simulations of mechanical properties and fracture of graphene: A review,” Computational Materials Science. 2022. link Times cited: 14 USED (low confidence) K. Cai, P. Wu, J. Shi, Z. Zhong, and Y. Zhang, “CNT-motor driven by competition between thermal fluctuation and REF,” International Journal of Mechanical Sciences. 2022. link Times cited: 4 USED (low confidence) K. M. Mukut, S. P. Roy, and E. Goudeli, “Molecular arrangement and fringe identification and analysis from molecular dynamics (MAFIA-MD): A tool for analyzing the molecular structures formed during reactive molecular dynamics simulation of hydrocarbons,” Comput. Phys. Commun. 2022. link Times cited: 2 USED (low confidence) R. Momen, R. Rezaee, B. Azizi, S. Rezaee, H. Hou, and X. Ji, “Evaluation of mechanical properties of multilayer graphyne-based structures as anode materials for lithium-ions batteries,” The European Physical Journal Plus. 2022. link Times cited: 10 USED (low confidence) K. K. Gupta, L. Roy, and S. Dey, “Hybrid machine-learning-assisted stochastic nano-indentation behaviour of twisted bilayer graphene,” Journal of Physics and Chemistry of Solids. 2022. link Times cited: 10 USED (low confidence) T. Wavrunek, Q. Peng, and N. Abu-Zahra, “Mechanical Properties and Buckling of Kagome Graphene under Tension: A Molecular Dynamics Study,” Crystals. 2022. link Times cited: 2 Abstract: Kagome graphene is a carbon allotrope similar to graphene, w… read moreAbstract: Kagome graphene is a carbon allotrope similar to graphene, with a single-atom thickness and a co-planar atomic structure. Despite interesting electronic properties, its mechanical behavior is still elusive. We have investigated the tensile properties of Kagome graphene under various strain rates and finite temperatures using molecular dynamics simulations. The Young’s modulus, ultimate tensile strength, fracture strain, and fracture toughness of the unsupported bulk material were measured as 96 GPa, 43 GPa, 0.05, and 1.9 J m−3, respectively, at room temperature and a strain rate of 109 s−1. Two deformation-stages were observed under tensile loading: normal and wrinkled. Initially, the Kagome graphene system stays in a co-planar structure without wrinkling until the tensile strain reaches 0.04, where it starts to wrinkle, unlike graphene. The wrinkle wavelength and magnitude suggest a very low bending rigidity, and wrinkle formation does not follow a rate predicted by continuum mechanics. Furthermore, the fracture mechanism of wrinkled Kagome graphene is briefly discussed. read less USED (low confidence) H. Almousa, Q. Peng, and A. Alsayoud, “A Molecular Dynamics Study of the Stability and Mechanical Properties of a Nano-Engineered Fuzzy Carbon Fiber Composite,” Journal of Composites Science. 2022. link Times cited: 0 Abstract: Carbon fiber-reinforced polymer composites are used in vario… read moreAbstract: Carbon fiber-reinforced polymer composites are used in various applications, and the interface of fibers and polymer is critical to the composites’ structural properties. We have investigated the impact of introducing different carbon nanotube loadings to the surfaces of carbon fibers and characterized the interfacial properties by molecular dynamics simulations. The carbon fiber (CF) surface structure was explicitly modeled to replicate the graphite crystallites’ interior consisting of turbostratic interconnected graphene multilayers. Then, single-walled carbon nanotubes and polypropylene chains were packed with the modeled CFs to construct a nano-engineered “fuzzy” CF composite. The mechanical properties of the CF models were calculated through uniaxial tensile simulations. Finally, the strength to peel the polypropylene from the nano-engineered CFs and interfacial energy were calculated. The interfacial strength and energy results indicate that a higher concentration of single-walled carbon nanotubes improves the interfacial properties. read less USED (low confidence) M. Dewapriya and R. E. Miller, “Quantum and classical molecular dynamics simulations of shocked polyurea and polyurethane,” Computational Materials Science. 2022. link Times cited: 6 USED (low confidence) J. Kim, G.-S. Kim, G. Heo, and K. Chang, “Defect Structure Classification of Neutron-Irradiated Graphite using Supervised Machine Learning,” Nuclear Engineering and Technology. 2022. link Times cited: 0 USED (low confidence) M. Dewapriya and R. Miller, “Molecular dynamics study on the shock induced spallation of polyethylene,” Journal of Applied Physics. 2022. link Times cited: 3 USED (low confidence) Z. Li, F. Zheng, L. Wang, F. Duan, and X. Mu, “Effect of hydrogen adsorption on the atomic-scale wear of few-layer graphene,” Tribology International. 2021. link Times cited: 6 USED (low confidence) W. Nishad, S. Subbiah, and N. Swaminathan, “A qualitative understanding of high intensity mechanical shearing and exfoliation of graphite nanoplatelets in a three-body contact using molecular dynamic simulations,” Journal of Manufacturing Processes. 2021. link Times cited: 1 USED (low confidence) W. Gong, R. Garg, R. Guo, S. Lee, T. Cohen-Karni, and S. Shen, “Thermal Transport in Multidimensional Silicon-Graphene Hybrid Nanostructures.,” ACS applied materials & interfaces. 2021. link Times cited: 3 Abstract: In this work, we fabricate multidimensional silicon-graphene… read moreAbstract: In this work, we fabricate multidimensional silicon-graphene hybrid nanostructures composed of three-dimensional (3D) out-of-plane graphene flakes on a silicon nanowire core. By changing the synthesis temperature (700 and 1100 °C) and time (5, 10, and 20 min), we obtain two different types of 3D graphene flakes with tunable dimensions and structure parameters. We characterize the thermal transport behavior of this hybrid multidimensional material in a broad temperature range of 20-460 K. With different morphologies and structures, the effective thermal conductivity of the silicon-graphene hybrid nanostructures varies from 1 to 7 W/(m·K) at room temperature. We also apply molecular dynamics simulation and density functional theory to elucidate the thermal transport mechanisms in the silicon-graphene hybrid nanostructures. read less USED (low confidence) H. Shoaib, Q. Peng, and A. Alsayoud, “Atomic Insights into Fracture Characteristics of Twisted Tri-Layer Graphene,” Crystals. 2021. link Times cited: 7 Abstract: Graphene twistronics have recently gained significant attent… read moreAbstract: Graphene twistronics have recently gained significant attention due their superconductive behavior as a consequence of their tunable electronic properties. Although the electronic properties of twisted graphene have been extensively studied, the mechanical properties and integrity of twisted trilayer graphene (tTLG) under loading is still elusive. We investigated the fracture mechanics of tTLG with a twist angle of ±1.53° utilizing molecular dynamics simulation. This twist angle was chosen because it is known to exhibit highly superconductive behavior. The results indicate that tTLG does not preserve the excellent mechanical properties typically associated with graphene, with toughness and fracture strain values much lower in comparison. The Young’s modulus was an exception with values relatively close to pristine graphene, whereas the tensile strength was found to be roughly half of the intrinsic strength of graphene. The fracture toughness, fracture strain and strength converge as the crack length increases, reaching 0.26 J/m3, 0.0217 and 39.9 GPa at a crack length of 8 nm, respectively. The Griffth critical strain energy is 19.98 J/m2 and the critical stress intensity factor Kc is 4.47 MPa M1/2, in good agreement with that of monolayer graphene in the experiment. Our atomic insights might be helpful in the material design of twisted trilayer graphene-based electronics. read less USED (low confidence) X. Zhang, H. Zhang, Z. Zong, Z. Li, and X. Chen, “From regular arrays of liquid metal nano-islands to single crystalline biatomic-layer gallium film: Molecular dynamics and first principle study,” Journal of Applied Physics. 2021. link Times cited: 0 Abstract: The two-dimensional (2D) materials provide an excellent plat… read moreAbstract: The two-dimensional (2D) materials provide an excellent platform for the study of the dimensional effect. The richer the types of 2D materials, the broader the unknown field we can explore. However, among the large number of 2D materials manufactured by humans, true single-crystalline (SC) atomically thin 2D metals are rare. The instability of SC 2D metal materials puts high demands on its fabrication process. By implementing molecular dynamics (MD) simulations, we proved that the SC biatomic-layer (BL) gallium film can be formed at the interface between two graphene layers. The Ga atoms deposited on the surface of the graphene on the copper substrate will spontaneously evolve into independent liquid nano-islands, and then cover the nano-island with a monolayer graphene. When the Ga nano-islands confined under the graphene layer are heated to 500 °C, they will expand into a BL Ga film, and finally, the entire system is cooled to room temperature to obtain the SCBL Ga film. It is found that these nano-islands are in the liquid state at ∼400 °C, but they undergo a phase transition and evolve into the solid state at ∼500°C. At the same time, the nano-islands also drop from 3D to 2D. In addition, the vertical heterostructure with moire superstructure is formed between the SCBL Ga and the top layer graphene. The calculations of the electronic properties show that the Dirac conical point of the graphene in the heterostructure is shifted below the Fermi level, which proves that SCBL Ga is able to induce semimetallic to metallic conversion in graphene, indicating SCBL Ga can be used for metal contacts in 2D devices. read less USED (low confidence) B. Goh, K. J. Kim, C.-L. Park, E. S. Kim, S.-H. Kim, and J. Choi, “In-plane thermal conductivity of multi-walled carbon nanotube yarns under mechanical loading,” Carbon. 2021. link Times cited: 10 USED (low confidence) K. Cai, Y. Yang, J. Shi, Z. Zhong, and Q. Qin, “Thermal stability of a nanoporous graphene membrane candidate from an orthogonal-diagonal nanotexture: A molecular dynamics test,” Applied Surface Science. 2021. link Times cited: 2 USED (low confidence) E. Annevelink, H. Johnson, and E. Ertekin, “Pathways to controlled 3D deformation of graphene: Manipulating the motion of topological defects,” Current Opinion in Solid State & Materials Science. 2021. link Times cited: 4 USED (low confidence) S. Attarian and S. Xiao, “Development of a 2NN-MEAM potential for boron.” 2021. link Times cited: 2 Abstract: In this paper, we present the first work in developing a sec… read moreAbstract: In this paper, we present the first work in developing a second nearest-neighbor modified embedded atom method (2NN-MEAM) potential function that can be used to model interatomic interactions in bo... read less USED (low confidence) A. Evseev et al., “MWCNT-based surfaces with tunable wettability obtained by He+ ion irradiation,” Surfaces and Interfaces. 2021. link Times cited: 8 USED (low confidence) P. Gao et al., “Millimeter-Scale and Billion-Atom Reactive Force Field Simulation on Sunway Taihulight,” IEEE Transactions on Parallel and Distributed Systems. 2020. link Times cited: 13 Abstract: Large-scale molecular dynamics (MD) simulations on supercomp… read moreAbstract: Large-scale molecular dynamics (MD) simulations on supercomputers play an increasingly important role in many research areas. With the capability of simulating charge equilibration (QEq), bonds and so on, Reactive force field (ReaxFF) enables the precise simulation of chemical reactions. Compared to the first principle molecular dynamics (FPMD), ReaxFF has far lower requirements on computational resources so that it can achieve higher efficiencies for large-scale simulations. In this article, we present our efforts on scaling ReaxFF on the Sunway TaihuLight Supercomputer (TaihuLight). We have carefully redesigned the force analysis and neighbor list building steps. By applying fine-grained optimizations we gain better single process performance. For the many-body interactions, we propose an isolated computation and update strategy and implement inverse trigonometric functions. For QEq, we implement a pipelined conjugate gradient (CG) approach to achieving better scalability. Furthermore, we reorganize the data layout and implement the update operation based on data locality in ReaxFF. Our experiments show that this approach can simulate chemical reactions with 1,358,954,496 atoms using 4,259,840 cores with a performance of 0.015 ns/day. To our best knowledge, this is the first realization of chemical reaction simulation with a millimeter-scale force field. read less USED (low confidence) T. C. O’Connor and M. Robbins, “Molecular models for creep in oriented polyethylene fibers.,” The Journal of chemical physics. 2020. link Times cited: 3 Abstract: Highly oriented and crystalline polyetheylene (PE) fibers ha… read moreAbstract: Highly oriented and crystalline polyetheylene (PE) fibers have a large failure stress under rapid tensile loading but exhibit significant creep at much smaller stresses that limits applications. A possible mechanism is slip of chains due to stress-enhanced, thermally activated nucleation of dislocations at chain ends in crystalline regions. Molecular dynamics simulations are used to parameterize a Frenkel-Kontorova model that provides analytic expressions for the limiting stress and activation energy for dislocation nucleation as a function of stress. Results from four commonly used hydrocarbon potentials are compared to show that the qualitative behavior is robust and estimate quantitative uncertainties. In all cases, the results can be described by an Eyring model with values of the zero-stress activation energy Ea 0≈1.5 eV and activation volume V* ≈ 45 Å3 that are consistent with the experimental results for increasingly crystalline materials. The limiting yield stress is ∼8 GPa. These results suggest that activated dislocation nucleation at chain ends is an important mechanism for creep in highly oriented PE fibers. read less USED (low confidence) L. Pascazio, J. W. Martin, K. Bowal, J. Akroyd, and M. Kraft, “Exploring the internal structure of soot particles using nanoindentation: A reactive molecular dynamics study,” Combustion and Flame. 2020. link Times cited: 19 USED (low confidence) S. Zhang and S. X. Hu, “Species Separation and Hydrogen Streaming upon Shock Release from Polystyrene under Inertial Confinement Fusion Conditions.,” Physical review letters. 2020. link Times cited: 8 Abstract: Shock release from inertial confinement fusion (ICF) shells … read moreAbstract: Shock release from inertial confinement fusion (ICF) shells poses a great challenge to single-fluid hydrodynamic equations, especially for describing materials composed of different ion species. This has been evidenced by a recent experiment [Haberberger et al., Phys. Rev. Lett. 123, 235001 (2019)PRLTAO0031-900710.1103/PhysRevLett.123.235001], in which low-density plasmas (10^{19} to 10^{20} cm^{-3}) are measured to move far ahead of what radiation-hydrodynamic simulations predict. To understand such experimental observations, we have performed large-scale nonequilibrium molecular-dynamics simulations of shock release in polystyrene (CH) at experimental conditions. These simulations revealed that upon shock releasing from the back surface of a CH foil, hydrogen can stream out of the bulk of the foil due to its mass being lighter than carbon. This released hydrogen, exhibiting a much broader velocity distribution than carbon, forms low-density plasmas moving in nearly constant velocities ahead of the in-flight shell, which is in quantitative agreement with the experimental measurements. Such kinetic effect of species separation is currently missing in single-fluid radiation-hydrodynamics codes for ICF simulations. read less 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) A. Stepanov et al., “Disordering of carbon nanotubes by ion bombardment,” Journal of Physics: Conference Series. 2020. link Times cited: 3 Abstract: In this work, the formation of defects during the ionic modi… read moreAbstract: In this work, the formation of defects during the ionic modification of carbon nanotubes was studied. It was shown that during the ionic modification of multiwalled carbon nanotubes, the defect formation mechanism is reduced not only to the formation of recoil atoms by ions, but also due to the thermal peak. It can be seen that the radial distribution function for the irradiated nanotube is significantly different from the radial distribution function of a heated 4000 K nanotube. In addition, disorder has a special character: in the case of ion irradiation, in contrast to heating. read less USED (low confidence) S. Carr, S. Fang, and E. Kaxiras, “Electronic-structure methods for twisted moiré layers,” Nature Reviews Materials. 2020. link Times cited: 133 USED (low confidence) F. Ebrahem, J. Stratmann, M. Stoffel, B. Markert, and F. Bamer, “Continuous Zachariasen carbon monolayers under tensile deformation: Insights from molecular dynamics simulations,” Extreme Mechanics Letters. 2020. link Times cited: 6 USED (low confidence) L. Zhang, Z. Song, B. Zhao, E. Villarreal, and H. Ban, “Fast atom effect on helium gas/graphite interfacial energy transfer,” Carbon. 2020. link Times cited: 4 USED (low confidence) Z. A. H. Goodwin, V. Vitale, X. Liang, A. Mostofi, and J. Lischner, “Hartree theory calculations of quasiparticle properties in twisted bilayer graphene,” Electronic Structure. 2020. link Times cited: 52 Abstract: A detailed understanding of interacting electrons in twisted… read moreAbstract: A detailed understanding of interacting electrons in twisted bilayer graphene (tBLG) near the magic angle is required to gain insights into the physical origin of the observed broken symmetry phases. Here, we present extensive atomistic Hartree theory calculations of the electronic properties of tBLG in the (semi-)metallic phase as function of doping and twist angle. Specifically, we calculate quasiparticle properties, such as the band structure, density of states (DOS) and local density of states (LDOS), which are directly accessible in photoemission and tunnelling spectroscopy experiments. We find that quasiparticle properties change significantly upon doping—an effect which is not captured by tight-binding theory. In particular, we observe that the partially occupied bands flatten significantly which enhances the density of states at the Fermi level. We predict a clear signature of this band flattening in the LDOS in the AB/BA regions of tBLG which can be tested in scanning tunneling experiments. We also study the dependence of quasiparticle properties on the dielectric environment of tBLG and discover that these properties are surprisingly robust as a consequence of the strong internal screening. Finally, we present a simple analytical expression for the Hartree potential which enables the determination of quasiparticle properties without the need for self-consistent calculations. read less USED (low confidence) J. Yan and S. Y. Chen, “Mechanical properties of monolayer antimony carbide: A molecular dynamics simulation,” Materials today communications. 2020. link Times cited: 0 USED (low confidence) A. Kolesnikova and K. Prihodchenko, “Modification of the molecular-mechanics method for realizing the interaction of carbon structures with potassium atoms,” BiOS. 2020. link Times cited: 0 Abstract: The theoretical molecular-mechanical method using the AIREBO… read moreAbstract: The theoretical molecular-mechanical method using the AIREBO energy potential was modernized to study the mechanical properties of porous carbon nanostructures doped with potassium atoms. The selection of coefficients was carried out by solving a minimax problem based on experimental data of the distances between the potassium and carbon atoms. The choice of this particular method for modifying and studying the mechanical properties of nanostructures is due to the necessity of calculating a large number of atoms with minimal time expenditures and with no loss of calculation accuracy. The study of mechanical properties was carried out depending on the size of the nanopores of the porous carbon nanostructure. The modernization consisted in the selection of weighting coefficients to describe the interaction between potassium and carbon atoms. Physical interaction is described by the Lennard-Jones potential. This modernization was performed to study the mechanical properties of carbon nanostructures of doped potassium atoms. read less USED (low confidence) I.-C. Yeh, L. Balzano, H. van der Werff, R. Mrozek, J. L. Lenhart, and J. Andzelm, “Effects of Finite Lengths of Chains on the Structural and Mechanical Properties of Polyethylene Fibers,” Macromolecules. 2020. link Times cited: 4 Abstract: We investigated the effects of finite lengths of polymer cha… read moreAbstract: We investigated the effects of finite lengths of polymer chains on the structural and mechanical properties of polyethylene (PE) fibers with atomistic molecular dynamics simulations. PE fiber models containing long but finite chains with different distributions of chain-end defects were prepared from the orthorhombic crystalline PE configuration. In our main PE fiber model, chain-end defects were uniformly spaced along the chain direction with chain ends located at boundaries of multiple crystalline regions, which is consistent with the distribution of chain ends found in semicrystalline PE. At the early stage of tensile deformations before the yield point, a mismatch of conformational preferences in the chain-end region of a chain and chain segments away from the chain-end regions in neighboring chains developed gradually. Near the yield point, this mismatch in conformational preferences triggered a yield behavior associated with chain slippage near the chain-end region and caused significant changes in ... read less USED (low confidence) Y. Yang, K. Cai, J. Shi, and Q. Qin, “Shrinkage-expansion of a tri-isometric knitting from graphene ribbons at finite temperature,” Materials & Design. 2020. link Times cited: 7 USED (low confidence) H. Li and P. S. Branicio, “Ultra-low friction of graphene/C60/graphene coatings for realistic rough surfaces,” Carbon. 2019. link Times cited: 13 USED (low confidence) A. Khajeh, Z. Chen, S. H. Kim, and A. Martini, “Effect of Ambient Chemistry on Friction at the Basal Plane of Graphite.,” ACS applied materials & interfaces. 2019. link Times cited: 10 Abstract: Graphite is widely used as a solid lubricant due to its laye… read moreAbstract: Graphite is widely used as a solid lubricant due to its layered structure which enables ultra-low friction. However, the lubricity of graphite is affected by ambient conditions and previous studies have shown a sharp contrast between frictional behavior in vacuum or dry environments compared to humid air. Here we studied the effect of organic gaseous species in the environment, specifically comparing the adsorption of phenol and pentanol vapor. Atomic force microscopy experiments and reactive molecular dynamics simulations showed that friction was larger with phenol than pentanol. The simulation results were analyzed to test multiple hypotheses to explain the friction difference and it was found that mechanical force-driven chemical bonding between the tip and phenol molecules plays a critical role. Bonding increases the number of phenol molecules in the contact which increases adhesion as well as the number of atoms in registry with the topmost graphene layer that act as pinning sites to resist sliding. The findings of this research provide insight into how the chemistry of the operating environment can affect the frictional behavior of graphite and layered materials more generally. read less USED (low confidence) S. Kumar, S. K. Pattanayek, and S. Das, “Reactivity-Controlled Aggregation of Graphene Nanoflakes in Aluminum Matrix: Atomistic Molecular Dynamics Simulation,” The Journal of Physical Chemistry C. 2019. link Times cited: 10 Abstract: Aluminum graphene nanoflakes composite depicts many useful p… read moreAbstract: Aluminum graphene nanoflakes composite depicts many useful properties such as excellent mechanical strength, lightweight, high electrical, thermal properties, etc. Aggregation and dispersion of graphene nanoflakes in aluminum matrix highly influence the above-mentioned properties. In this paper, aggregation of graphene nanoflakes in aluminum matrix has been studied using molecular dynamics simulation. During simulations, adaptive intermolecular reactive empirical bond order (AIREBO) and embedded atom method force field were used for graphene nanoflakes and aluminum, respectively. AIREBO potential is capable of reproducing sp2–sp2 (covalent) bond formation or breaking between the reactive edge of graphene nanoflakes. The reactive edges of graphene nanoflakes form covalent bond with the neighboring graphene that produces a unique interconnected network in aluminum matrix. However, reactivity of graphene edge exclusively depends on the interfacial interaction between graphene and aluminum. Further, interfaci... read less USED (low confidence) B. Morris, M. Becton, and X. Wang, “Mechanical abnormality in graphene-based lamellar superstructures,” Carbon. 2018. link Times cited: 14 USED (low confidence) J. Li, W. Cao, Z. Wang, M. Ma, and J. Luo, “Origin of hydration lubrication of zwitterions on graphene.,” Nanoscale. 2018. link Times cited: 22 Abstract: Formation of a hydration layer on charge sites can support n… read moreAbstract: Formation of a hydration layer on charge sites can support normal pressure, and meanwhile it retains excellent fluidity to provide efficient boundary lubrication; however, it is limited to the sliding system between two similarly charged surfaces. In the present study, we report extremely low friction as the zwitterions in a lipid bilayer slide on the topmost graphene layer of graphite across pure water, with the friction coefficient falling to the level of 0.001, which provides direct evidence that hydration lubrication is effective even between such dissimilar surfaces. The origin of hydration lubrication on graphene was studied by atomic force microscopy and molecular dynamics simulation simultaneously. It reveals that a subnanometer hydration layer is confined between zwitterions and graphene, which remains as a liquid phase under normal pressure. The shear occurs between water molecules and graphene because of the extremely low shear strength of the water/graphene interface, which contributes to extremely low friction. Our finding demonstrates that the formation of a hydration layer is possible to lubricate layered materials efficiently, which has potential implications for designing efficient boundary lubrication with layered materials. read less USED (low confidence) I. Srivastava, B. L. Peters, J. Lane, H. Fan, K. Salerno, and G. Grest, “Mechanics of Gold Nanoparticle Superlattices at High Hydrostatic Pressures,” The Journal of Physical Chemistry C. 2018. link Times cited: 9 Abstract: Pressure-driven assembly of ligand-grafted gold nanoparticle… read moreAbstract: Pressure-driven assembly of ligand-grafted gold nanoparticle superlattices is a promising approach for fabricating gold nanostructures, such as nanowires and nanosheets. Optimizing this fabrication... read less USED (low confidence) H. Dong, Z. Wang, T. C. O’Connor, A. Azoug, M. Robbins, and T. Nguyen, “Micromechanical models for the stiffness and strength of UHMWPE macrofibrils,” Journal of the Mechanics and Physics of Solids. 2018. link Times cited: 15 USED (low confidence) T. C. O’Connor, R. Elder, Y. R. Sliozberg, T. Sirk, J. Andzelm, and M. Robbins, “Molecular origins of anisotropic shock propagation in crystalline and amorphous polyethylene,” Physical Review Materials. 2018. link Times cited: 16 USED (low 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 USED (low confidence) O. Glukhova and M. Slepchenkov, “Phospholipid dynamics in graphene of different topologies: predictive modeling,” BiOS. 2017. link Times cited: 0 Abstract: The subject of our scientific interest is the dynamics of th… read moreAbstract: The subject of our scientific interest is the dynamics of the phospholipid molecules into a corrugated graphene sheet. According to our assumption by changing the topology of graphene properly it is possible to find the ways for management of the selective localization of phospholipid molecules to form the desired configuration of these structures. We considered DPPC (dipalmitoylphosphatidylcholine) phospholipids, which are the part of cell membranes and lipoproteins. We investigated the behavior of the phospholipids on the graphene sheet consisting of 1710 atoms with the size of 6.9 nm along the zigzag edge and 6.25 nm along the armchair edge. The numerical experiment was carried out using the original AMBER/AIREBO hybrid method with Lennard-Jones potential to describe the interaction between unbound atoms of different structures. The temperature was maintained at 300 K during the numerical experiment. All numerical experiments were performed using KVAZAR software system. We considered several cases of corrugated graphene with different width and dept of the corrugation. Special attention in our work was paid to the orientation of the phospholipids in the plane of graphene sheet. read less USED (low 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 USED (low confidence) T. C. O’Connor and M. Robbins, “Chain Ends and the Ultimate Strength of Polyethylene Fibers.,” ACS macro letters. 2015. link Times cited: 40 Abstract: We use large scale molecular dynamics (MD) simulations to de… read moreAbstract: We use large scale molecular dynamics (MD) simulations to determine the tensile yield mechanism of orthorhombic polyethylene (PE) crystals with finite chains spanning 102-104 carbons in length. We find the yield stress σy saturates for long chains at 6.3 GPa, agreeing well with experiments. We show chains do not break, but always yield by slip, after nucleation of 1D dislocations at chain ends. Dislocations are accurately described by a Frenkel-Kontorova model parametrized by the mechanical properties of an ideal crystal. We compute a dislocation core size ξ ≈ 25 Å and determine the high and low strain rate limits of σy. Our results suggest characterizing the 1D dislocations of polymer crystals as an efficient method for numerically predicting the ultimate tensile strength of aligned fibers. read less 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) M. A. Rahman, “STUDY OF ANISOTROPIC THERMAL CONDUCTIVITY OF GAS ADSORBED TWO DIMENSIONAL COVALENT ORGANIC FRAMEWORKS.” 2023. link Times cited: 0 Abstract: The horizon in material science has expanded drastically by … read moreAbstract: The horizon in material science has expanded drastically by the prospect of stacking two dimensional (2D) materials into vertical stacks. One such emerging class of materials are 2D covalent organic frameworks (COFs), which have already established themselves as game-changing porous polymeric crystals due to their exceptional physical properties such as high porosities and large surface areas with additional flexibility of precisely controlling the functional building blocks. These unique properties have made COFs ideal candidates for a plethora of applications, such as gas separation, adsorption and storage, drug delivery, and as solid-state electrolytes for upcoming energy storage technologies. However, the excessive heat generation due to the adsorption of guest species can severely limit their suitability in aforementioned applications. Therefore, it is crucial to find innovative ways to modulate their thermal properties by fully comprehending the essential characteristics that control the effectiveness of energy transfer efficacies in these materials for successful implementation of COFs in practical devices. In this work, we carry out systematic atomistic simulations to study the influence of pore geometry of the 2D COFs on their anisotropic heat transfer mechanisms and to answer the long-standing debate on whether the guest molecules increase or decrease their overall thermal conductivity. We show that the thermal conductivity can either increase due to additional heat channels introduced by the gas adsorbates or decrease from enhanced phonon scattering resulting from the interactions between the gas and the solid pore walls of the COFs. More specifically, we conduct atomistic simulations on pristine and gas adsorbed COF structures with different pore sizes and reveal that for COFs with relatively larger pore sizes (≳2 nm), despite the reduction of the thermal conductivity of the solid framework due to solid-gas scattering, the increase in contribution to the overall thermal conductivity by the gas adsorbates (methane) in the 1D channel can dramatically enhance the cross-plane thermal conductivity. On the other hand, for COFs with relatively smaller pores (≲2 nm), the increase in solid-gas scattering results in a monotonic reduction in the cross-plane and in-plane thermal conductivity. We attribute the increase in cross-plane thermal conductivity of the larger-pore COFs to the elevated heat conduction by the lower-frequency vibrations (≲0.5 THz) compared to the total frequency range of the gas molecules confined in the larger pore. However, due to substantial broadening of the vibrational modes to higher frequencies, these low frequency vibrations of the gas adsorbates do not contribute to the heat conduction in small-pore COFs. Through our results we reveal the complex relationship between the pore geometry, diffusivity of confined gas molecules and solid-gas interactions, which dictate the tunable thermal conductivities of these porous crystals. Additionally, our results shed light on the inherent nature of gas diffusion and heat transfer in porous organic frameworks, and providing a new path forward to tune the thermal conductivity of 2D COFs by modulating the gas diffusion inside the pores. Our findings can have major implications in designing 2D polymeric crystals with desired thermal conductivities for efficient gas storage, separation, and catalysis applications. read less USED (low confidence) S. Kumar and T. Mishra, “Organization of Bio-Molecules in Bulk and Over the Nano-Substrate: Perspective to the Molecular Dynamics Simulations.” 2020. link Times cited: 0 USED (low confidence) A. David, A. de Nicola, U. Tartaglino, G. Milano, and G. Raos, “Viscoelasticity of Short Polymer Liquids from Atomistic Simulations,” Journal of The Electrochemical Society. 2019. link Times cited: 16 Abstract: The viscosity − or more generally the viscoelasticity − of p… read moreAbstract: The viscosity − or more generally the viscoelasticity − of polymer liquids is a key property for the processing as well as the performance of these materials. Molecular theories and numerical methods can provide these quantities, but they all require certain input parameters that nowadays are typically obtained by experiment. In the long term, it would be desirable to obtain these parameters or the whole viscoelastic response by purely computational methods, enabling a full “in silico” design of new materials and processes. In this perspective, we present several test calculations of the viscosity of n-hexadecane, a short-chain analogue of polyethylene. Our calculations are based on both equilibrium and non-equilibrium molecular dynamics (MD) simulations, which are applied to models based on a united-atom force field, a conventional atomistic force field, and the AIREBO-M reactive force field. We compare both the computational cost of the different strategies and the reliability of the different models and we provide some general guidelines for their application to more complex systems. © The Author(s) 2019. Published by ECS. This is an open access article distributed under the terms of the Creative Commons Attribution 4.0 License (CC BY, http://creativecommons.org/licenses/by/4.0/), which permits unrestricted reuse of the work in any medium, provided the original work is properly cited. [DOI: 10.1149/2.0371909jes] read less USED (low confidence) T. Mattsson, K. Cochrane, J. Lane, and S. Root, “Simulations of Hydrocarbon Polymers Related to Compression Experiments on Sandia’s Z Machine,” Computational Approaches for Chemistry Under Extreme Conditions. 2019. link Times cited: 2 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) O. Glukhova, “Molecular Dynamics as the Tool for Investigation of Carbon Nanostructures Properties.” 2017. link Times cited: 18 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 NOT USED (low confidence) X. Shi, X. He, and X. Liu, “Understanding the Mechanism of the Structure-Dependent Mechanical Performance of Carbon-Nanotube-Based Hierarchical Networks from a Deformation Mode Perspective,” Nanomaterials. 2023. link Times cited: 0 Abstract: Carbon nanotube (CNT)-based networks have wide applications,… read moreAbstract: Carbon nanotube (CNT)-based networks have wide applications, in which structural design and control are important to achieve the desired performance. This paper focuses on the mechanism behind the structure-dependent mechanical performance of a CNT-based hierarchical network, named a super carbon nanotube (SCNT), which can provide valuable guidance for the structural design of CNT-based networks. Through molecular dynamic (MD) simulations, the mechanical properties of the SCNTs were found to be affected by the arrangement, length and chirality of the CNTs. Different CNT arrangements cause variations of up to 15% in the ultimate tensile strains of the SCNTs. The CNT length determines the tangent elastic modulus of the SCNTs at the early stage. Changing the CNT chirality could transform the fracture modes of the SCNT from brittle to ductile. The underlying mechanisms were found to be associated with the deformation mode of the SCNTs. All the SCNTs undergo a top-down hierarchical deformation process from the network-level angle variations to the CNT-level elongations, but some vital details vary, such as the geometrical parameters. The CNT arrangement induces different deformation contributors of the SCNTs. The CNT length affects the beginning point of the CNT elongation deformation. The CNT chirality plays a crucial role in the stability of the junction’s atomic topology, where the crack propagation commences. read less 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) W. Jiang et al., “Anisotropic Interlayer Force Field for Group-VI Transition Metal Dichalcogenides.,” The journal of physical chemistry. A. 2023. link Times cited: 0 Abstract: An anisotropic interlayer force field that describes the int… read moreAbstract: An anisotropic interlayer force field that describes the interlayer interactions in homogeneous and heterogeneous interfaces of group-VI transition metal dichalcogenides (MX2, where M = Mo, W, and X = S, Se) is presented. The force field is benchmarked against density functional theory calculations for bilayer systems within the Heyd-Scuseria-Ernzerhof hybrid density functional approximation, augmented by a nonlocal many-body dispersion treatment of long-range correlation. The parametrization yields good agreement with the reference calculations of binding energy curves and sliding potential energy surfaces. It is found to be transferable to transition metal dichalcogenide (TMD) junctions outside of the training set that contain the same atom types. Calculated bulk moduli agree with most previous dispersion-corrected density functional theory predictions, which underestimate the available experimental values. Calculated phonon spectra of the various junctions under consideration demonstrate the importance of appropriately treating the anisotropic nature of the layered interfaces. Considering our previous parametrization for MoS2, the anisotropic interlayer potential enables accurate and efficient large-scale simulations of the dynamical, tribological, and thermal transport properties of a large set of homogeneous and heterogeneous TMD interfaces. read less NOT USED (low confidence) S. Schmitt, F. Fleckenstein, H. Hasse, and S. Stephan, “Comparison of Force Fields for the Prediction of Thermophysical Properties of Long Linear and Branched Alkanes.,” The journal of physical chemistry. B. 2023. link Times cited: 11 Abstract: The prediction of thermophysical properties at extreme condi… read moreAbstract: The prediction of thermophysical properties at extreme conditions is an important application of molecular simulations. The quality of these predictions primarily depends on the quality of the employed force field. In this work, a systematic comparison of classical transferable force fields for the prediction of different thermophysical properties of alkanes at extreme conditions, as they are encountered in tribological applications, was carried out using molecular dynamics simulations. Nine transferable force fields from three different classes were considered (all-atom, united-atom, and coarse-grained force fields). Three linear alkanes (n-decane, n-icosane, and n-triacontane) and two branched alkanes (1-decene trimer and squalane) were studied. Simulations were carried out in a pressure range between 0.1 and 400 MPa at 373.15 K. For each state point, density, viscosity, and self-diffusion coefficient were sampled, and the results were compared to experimental data. The Potoff force field yielded the best results. read less NOT USED (low 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 (low confidence) M. A. Rahman, C. Dionne, and A. Giri, “Pore Size Dictates Anisotropic Thermal Conductivity of Two-Dimensional Covalent Organic Frameworks with Adsorbed Gases.,” ACS applied materials & interfaces. 2022. link Times cited: 11 Abstract: Two-dimensional covalent organic frameworks (2D COFs) are a … read moreAbstract: Two-dimensional covalent organic frameworks (2D COFs) are a class of modular polymeric crystals with high porosities and large surface areas, which position them as ideal candidates for applications in gas storage and separation technologies. In this work, we study the influence of pore geometry on the anisotropic heat transfer mechanisms in 2D COFs through systematic atomistic simulations. More specifically, by studying COFs with varying pore sizes and gas densities, we demonstrate that the cross-plane thermal conductivity along the direction of the laminar pores can either be decreased due to solid-gas scattering (for COFs with relatively smaller pores that are ≲2 nm) or increased due to additional heat transfer pathways introduced by the gas adsorbates (for COFs with relatively larger pores). Our simulations on COF/methane systems reveal the intricate relationship among gas diffusivities, pore geometries, and solid-gas interactions dictating the modular thermal conductivities in these materials. Along with the understanding of the fundamental nature of gas diffusion and heat conduction in the porous framework crystals, our results can also help guide the design of efficient 2D polymeric crystals for applications with improved gas storage, catalysis, and separation capabilities. read less NOT USED (low confidence) M. Müser, S. Sukhomlinov, and L. Pastewka, “Interatomic potentials: achievements and challenges,” Advances in Physics: X. 2022. link Times cited: 12 Abstract: ABSTRACT Interatomic potentials approximate the potential en… read moreAbstract: ABSTRACT Interatomic potentials approximate the potential energy of atoms as a function of their coordinates. Their main application is the effective simulation of many-atom systems. Here, we review empirical interatomic potentials designed to reproduce elastic properties, defect energies, bond breaking, bond formation, and even redox reactions. We discuss popular two-body potentials, embedded-atom models for metals, bond-order potentials for covalently bonded systems, polarizable potentials including charge-transfer approaches for ionic systems and quantum-Drude oscillator models mimicking higher-order and many-body dispersion. Particular emphasis is laid on the question what constraints ensue from the functional form of a potential, e.g., in what way Cauchy relations for elastic tensor elements can be violated and what this entails for the ratio of defect and cohesive energies, or why the ratio of boiling to melting temperature tends to be large for potentials describing metals but small for short-ranged pair potentials. The review is meant to be pedagogical rather than encyclopedic. This is why we highlight potentials with functional forms sufficiently simple to remain amenable to analytical treatments. Our main objective is to provide a stimulus for how existing approaches can be advanced or meaningfully combined to extent the scope of simulations based on empirical potentials. Graphical abstract read less NOT USED (low confidence) M. Ha, A. Hajibabaei, S. Pourasad, and K. S. Kim, “Sparse Gaussian Process Regression-Based Machine Learned First-Principles Force-Fields for Saturated, Olefinic, and Aromatic Hydrocarbons,” ACS Physical Chemistry Au. 2022. link Times cited: 4 Abstract: Universal machine learning (ML) interatomic potentials (IAPs… read moreAbstract: Universal machine learning (ML) interatomic potentials (IAPs) for saturated, olefinic, and aromatic hydrocarbons are generated by using the Sparse Gaussian process regression algorithm. The universal potentials are obtained by combining the potentials for the previously trained alkane/polyene systems and the potentials generated with the presently trained cyclic/aromatic hydrocarbon systems, along with the newly trained cross-terms between the two systems. The ML-IAPs have been trained using the PBE + D3 level of density functional theory for the on-the-fly adaptive sampling of various hydrocarbon molecules and these clusters composed of small molecules. We tested the ML-IAPs and found that they correctly predicted the structures and energies of the β-carotene monomer and dimer. Also, the simulations of liquid ethylene reproduced the molecular volume and the simulations of toluene crystals reproduced higher stability of the α-phase over the β-phase. These ab initio-level force-fields could eventually evolve toward universal organic/polymeric/biomolecular systems. read less NOT USED (low confidence) A. Aghajamali and A. Karton, “Superior performance of the machine-learning GAP force field for fullerene structures,” Structural Chemistry. 2022. link Times cited: 3 NOT USED (low confidence) G. Raos and B. Zappone, “Polymer Adhesion: Seeking New Solutions for an Old Problem,” Macromolecules. 2021. link Times cited: 38 Abstract: : Polymer adhesion is ubiquitous in both the natural world a… read moreAbstract: : Polymer adhesion is ubiquitous in both the natural world and human technology. It is also a complex multiscale phenomenon, such that the solution of adhesion problems requires a convergence of chemistry, physics, and engineering. In this Perspective, we provide an overview of some of the fundamental concepts that have emerged in the fi eld of polymer adhesion, discuss recent work, and identify challenges in three speci fi c areas: (a) theories and simulations, with an emphasis on problems involving chain scission; (b) experimental methods for measuring forces and characterizing interfaces at the molecular scale; and (c) strategies inspired by living organisms to generate underwater adhesion. read less NOT USED (low confidence) P. Gao et al., “lMFF: Efficient and Scalable layered Materials Force Field on Heterogeneous Many-Core Processors,” SC21: International Conference for High Performance Computing, Networking, Storage and Analysis. 2021. link Times cited: 7 Abstract: LAMMPS is one of the most popular Molecular Dynamic (MD) pac… read moreAbstract: LAMMPS is one of the most popular Molecular Dynamic (MD) packages and is widely used in the field of physics, chemistry and materials simulation. Layered Materials Force Field (LMFF) is our expansion of the LAMMPS potential function based on the Tersoff potential and inter-layer potential (ILP) in LAMMPS. LMFF is designed to study layered materials such as graphene and boron hexanitride. It is universal and does not depend on any platform. We have also carried out a series of optimizations on LMFF and the optimization work is carried out on the new generation of Sunway supercomputer, called SWLMFF. Experiments show that our implementation is efficient, scalable and portable. When generic LMFF is ported to Intel Xeon Gold 6278C, $2\times$ performance improvement is achieved. For the optimized SWLMFF, the overall performance improvement is nearly $200-330\times$ compared to the original ILP and Tersoff potentials. And SWLMFF has good parallel efficiency of 95%-100% under weak scaling with 2.7 million atoms on a single process. The maximum atomic system simulated by SWLMFF is close to $2^{31}$ atoms. And nanosecond simulations in one day can be realized. read less NOT USED (low confidence) W. Ouyang et al., “Anisotropic Interlayer Force Field for Transition Metal Dichalcogenides: The Case of Molybdenum Disulfide,” Journal of Chemical Theory and Computation. 2021. link Times cited: 12 Abstract: An anisotropic interlayer force field that describes the int… read moreAbstract: An anisotropic interlayer force field that describes the interlayer interactions in molybdenum disulfide (MoS2) is presented. The force field is benchmarked against density functional theory calculations for both bilayer and bulk systems within the Heyd–Scuseria–Ernzerhof hybrid density functional approximation, augmented by a nonlocal many-body dispersion treatment of long-range correlation. The parametrization yields good agreement with the reference calculations of binding energy curves and sliding potential energy surfaces for both bilayer and bulk configurations. Benchmark calculations for the phonon spectra of bulk MoS2 provide good agreement with experimental data, and the calculated bulk modulus falls in the lower part of experimentally measured values. This indicates the accuracy of the interlayer force field near equilibrium. Under external pressures up to 20 GPa, the developed force field provides a good description of compression curves. At higher pressures, deviations from experimental data grow, signifying the validity range of the developed force field. read less NOT USED (low confidence) Y. A. Timoshina, E. Voznesensky, and V. S. Zheltukhin, “MATHEMATICAL MODEL OF THE INTERACTION OF LOW-ENERGY INERT GAS IONS WITH POLYPROPYLENE IN RADIO-FREQUENCY PLASMA OF LOW PRESSURE,” Technologies & Quality. 2021. link Times cited: 2 Abstract: Results of the molecular dynamic simulation of the interacti… read moreAbstract: Results of the molecular dynamic simulation of the interaction of low-energy ions (from 10 to 100 eV) with the surface of polypropylene fibrous materials in low pressure radio-frequency (RF) argon plasma is presented. A full-atomic model using the LAMMPS classical molecular dynamics code was made. As a result of numerical calculations, it was found that argon ion bombardment initiates the breaking both of an intermolecular and intramolecular bond of polypropylene with sputtered particles being the hydrocarbon radicals and single atoms. The depth of implantation of the ion is determined, the change in the kinetic energy of the argon atom and the temperature of the simulated cell is obtained. read less NOT USED (low confidence) C. G. Bresnahan, G. Jenness, R. Kumar, and M. Shukla, “Introductory Roadmap to Current Reactive Force-Field Methodologies,” Practical Aspects of Computational Chemistry V. 2021. link Times cited: 0 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) J. Li, W. Cao, J. Li, and M. Ma, “Fluorination to enhance superlubricity performance between self-assembled monolayer and graphite in water.,” Journal of colloid and interface science. 2021. link Times cited: 13 NOT USED (low confidence) S. Kumar, T. Mishra, and A. Mahata, “Manipulation of mechanical properties of monolayer molybdenum disulfide: Kirigami and hetero-structure based approach,” Materials Chemistry and Physics. 2020. link Times cited: 4 NOT USED (low confidence) W. Ouyang et al., “Mechanical and Tribological Properties of Layered Materials Under High Pressure: Assessing the Importance of Many-Body Dispersion Effects.,” Journal of chemical theory and computation. 2019. link Times cited: 33 Abstract: The importance of many-body dispersion effects in layered ma… read moreAbstract: The importance of many-body dispersion effects in layered materials subjected to high external loads is evaluated. State-of-the-art many-body dispersion density functional theory calculations performed for graphite, hexagonal boron nitride, and their hetero-structures were used to fit the parameters of a classical registry-dependent interlayer potential. Using the latter, we performed extensive equilibrium molecular dynamics simulations and studied the mechanical response of homogeneous and heterogeneous bulk models under hydrostatic pressures up to 30 GPa. Comparison with experimental data demonstrates that the reliability of the many-body dispersion model extends deep into the sub-equilibrium regime. Friction simulations demonstrate the importance of many-body dispersion effects for the accurate description of the tribological properties of layered materials interfaces under high pressure. read less NOT USED (low confidence) N. Kondratyuk and V. Pisarev, “Calculation of viscosities of branched alkanes from 0.1 to 1000 MPa by molecular dynamics methods using COMPASS force field,” Fluid Phase Equilibria. 2019. link Times cited: 49 NOT USED (low confidence) J. Harrison, J. Schall, S. Maskey, P. Mikulski, M. T. Knippenberg, and B. Morrow, “Review of force fields and intermolecular potentials used in atomistic computational materials research,” Applied Physics Reviews. 2018. link Times cited: 99 Abstract: Molecular simulation is a powerful computational tool for a … read moreAbstract: Molecular simulation is a powerful computational tool for a broad range of applications including the examination of materials properties and accelerating drug discovery. At the heart of molecular simulation is the analytic potential energy function. These functions span the range of complexity from very simple functions used to model generic phenomena to complex functions designed to model chemical reactions. The complexity of the mathematical function impacts the computational speed and is typically linked to the accuracy of the results obtained from simulations that utilize the function. One approach to improving accuracy is to simply add more parameters and additional complexity to the analytic function. This approach is typically used in non-reactive force fields where the functional form is not derived from quantum mechanical principles. The form of other types of potentials, such as the bond-order potentials, is based on quantum mechanics and has led to varying levels of accuracy and transferability. When selecting a potential energy function for use in molecular simulations, the accuracy, transferability, and computational speed must all be considered. In this focused review, some of the more commonly used potential energy functions for molecular simulations are reviewed with an eye toward presenting their general forms, strengths, and weaknesses.Molecular simulation is a powerful computational tool for a broad range of applications including the examination of materials properties and accelerating drug discovery. At the heart of molecular simulation is the analytic potential energy function. These functions span the range of complexity from very simple functions used to model generic phenomena to complex functions designed to model chemical reactions. The complexity of the mathematical function impacts the computational speed and is typically linked to the accuracy of the results obtained from simulations that utilize the function. One approach to improving accuracy is to simply add more parameters and additional complexity to the analytic function. This approach is typically used in non-reactive force fields where the functional form is not derived from quantum mechanical principles. The form of other types of potentials, such as the bond-order potentials, is based on quantum mechanics and has led to varying levels of accuracy and transferabilit... read less NOT 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 NOT USED (low confidence) P. Chandra, L. Pandey, S. Das, V. Soni, J. Bellare, and H. Lau, “Biointerface Engineering: Prospects in Medical Diagnostics and Drug Delivery,” Biointerface Engineering: Prospects in Medical Diagnostics and Drug Delivery. 2020. link Times cited: 8 NOT USED (high confidence) F. Polewczyk, J.-M. Leyssale, and P. Lafourcade, “Temperature-dependent elasticity of single crystalline graphite,” Computational Materials Science. 2023. link Times cited: 1 NOT USED (high confidence) H. Zhai and J. Yeo, “Multiscale mechanics of thermal gradient coupled graphene fracture: A molecular dynamics study,” International Journal of Applied Mechanics. 2022. link Times cited: 2 Abstract: The thermo-mechanical coupling mechanism of graphene fractur… read moreAbstract: The thermo-mechanical coupling mechanism of graphene fracture under thermal gradients possesses rich applications whereas is hard to study due to its coupled non-equilibrium nature. We employ non-equilibrium molecular dynamics to study the fracture of graphene by applying a fixed strain rate under different thermal gradients by employing different potential fields. It is found that for AIREBO and AIREBO-M, the fracture stresses do not strictly follow the positive correlations with the initial crack length. Strain-hardening effects are observed for"REBO-based"potential models of small initial defects, which is interpreted as blunting effect observed for porous graphene. The temperature gradients are observed to not show clear relations with the fracture stresses and crack propagation dynamics. Quantized fracture mechanics verifies our molecular dynamics calculations. We provide a unique perspective that the transverse bond forces share the loading to account for the nonlinear increase of fracture stress with shorter crack length. Anomalous kinetic energy transportation along crack tips is observed for"REBO-based"potential models, which we attribute to the high interatomic attractions in the potential models. The fractures are honored to be more"brittle-liked"carried out using machine learning interatomic potential (MLIP), yet incapable of simulating post-fracture dynamical behaviors. The mechanical responses using MLIP are observed to be not related to temperature gradients. The temperature configuration of equilibration simulation employing the dropout uncertainty neural network potential with a dropout rate of 0.1 is reported to be the most accurate compared with the rest. This work is expected to inspire further investigation of non-equilibrium dynamics in graphene with practical applications in various engineering fields. read less NOT USED (high confidence) S. Zhang et al., “Species separation in polystyrene shock release evidenced by molecular-dynamics simulations and laser-drive experiments,” Physical Review Research. 2022. link Times cited: 0 NOT USED (high confidence) G. S. Dhaliwal, P. Nair, and C. V. Singh, “Machine learned interatomic potentials using random features,” npj Computational Materials. 2022. link Times cited: 10 NOT USED (high confidence) R. Vacher and A. S. de Wijn, “Nanoscale friction and wear of a polymer coated with graphene,” Beilstein Journal of Nanotechnology. 2022. link Times cited: 3 Abstract: Friction and wear of polymers at the nanoscale is a challeng… read moreAbstract: Friction and wear of polymers at the nanoscale is a challenging problem due to the complex viscoelastic properties and structure. Using molecular dynamics simulations, we investigate how a graphene sheet on top of the semicrystalline polymer polyvinyl alcohol affects the friction and wear. Our setup is meant to resemble an AFM experiment with a silicon tip. We have used two different graphene sheets, namely an unstrained, flat sheet, and one that has been crumpled before being deposited on the polymer. The graphene protects the top layer of the polymer from wear and reduces the friction. The unstrained flat graphene is stiffer, and we find that it constrains the polymer chains and reduces the indentation depth. read less NOT USED (high confidence) A. Tsukanov and N. Brilliantov, “Collision of nanoparticles of covalently bound atoms: Impact of stress-dependent adhesion.,” Physical review. E. 2021. link Times cited: 3 Abstract: The impact of nanoparticles (NPs) composed of atoms with cov… read moreAbstract: The impact of nanoparticles (NPs) composed of atoms with covalent bonding is investigated numerically and theoretically. We use recent models of covalent bonding of carbon atoms and elaborate a numerical model of amorphous carbon (a-C) NPs, which may be applied for modeling soot particles. We compute the elastic moduli of the a-C material which agree well with the available data. We reveal an interesting phenomenon-stress-dependent adhesion, which refers to stress-enhanced formation of covalent bonds between contacting surfaces. We observe that the effective adhesion coefficient linearly depends on the maximal stress between the surfaces and explain this dependence. We compute the normal restitution coefficient for colliding NPs and explore the dependence of the critical velocity, demarcating bouncing and aggregative collisions, on the NP radius. Using the obtained elastic and stress-dependent adhesive coefficients we develop a theory for the critical velocity. The predictions of the theory agree very well with the simulation results. read less NOT USED (high confidence) Y. Tanuma, T. Maekawa, and C. Ewels, “Methodological Investigation for Hydrogen Addition to Small Cage Carbon Fullerenes,” Crystals. 2021. link Times cited: 2 Abstract: Hydrogenated small fullerenes (Cn, n<60) are of interest as … read moreAbstract: Hydrogenated small fullerenes (Cn, n<60) are of interest as potential astrochemical species, and as intermediates in hydrogen catalysed fullerene growth. However computational identification of key stable species is difficult due to the vast combinatorial space of structures. In this study we explore routes to predict stable hydrogenated small fullerenes. We show that neither local fullerene geometry nor local electronic structure analysis are able to correctly predict subsequent low energy hydrogenation sites, and indeed sequential stable addition searches also sometimes fail to identify most stable hydrogenated fullerene isomers. Of the empirical and semi-empirical methods tested, GFN2-xTB consistently gives highly accurate energy correlation (r>0.99) to full DFT-LDA calculations at a fraction of the computational cost. This allows identification of the most stable hydrogenated fullerenes up to 4H for four fullerenes, namely two isomers of C28 and C40, via “brute force” systematic testing of all symmetry inequivalent combinations. The approach shows promise for wider systematic studies of smaller hydrogenated fullerenes. read less NOT USED (high confidence) R. Kumar et al., “Harnessing autocatalytic reactions in polymerization and depolymerization,” MRS Communications. 2021. link Times cited: 3 Abstract: Autocatalysis and its relevance to various polymeric systems… read moreAbstract: Autocatalysis and its relevance to various polymeric systems are discussed by taking inspiration from biology. A number of research directions related to synthesis, characterization, and multi-scale modeling are discussed in order to harness autocatalytic reactions in a useful manner for different applications ranging from chemical upcycling of polymers (depolymerization and reconstruction after depolymerization), self-generating micelles and vesicles, and polymer membranes. Overall, a concerted effort involving in situ experiments, multi-scale modeling, and machine learning algorithms is proposed to understand the mechanisms of physical and chemical autocatalysis. It is argued that a control of the autocatalytic behavior in polymeric systems can revolutionize areas such as kinetic control of the self-assembly of polymeric materials, synthesis of self-healing and self-immolative polymers, as next generation of materials for a sustainable circular economy. 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) J. Kadupitiya and V. Jadhao, “Probing the Rheological Properties of Liquids Under Conditions of Elastohydrodynamic Lubrication Using Simulations and Machine Learning,” Tribology Letters. 2021. link Times cited: 11 NOT USED (high confidence) Z. A. H. Goodwin et al., “Flat bands, electron interactions, and magnetic order in magic-angle mono-trilayer graphene,” Physical Review Materials. 2021. link Times cited: 11 Abstract: Zachary A. H. Goodwin,1,* Lennart Klebl ,2,* Valerio Vitale,… read moreAbstract: Zachary A. H. Goodwin,1,* Lennart Klebl ,2,* Valerio Vitale,1 Xia Liang ,1 Vivek Gogtay,1 Xavier van Gorp,1 Dante M. Kennes ,2,3 Arash A. Mostofi ,1 and Johannes Lischner 1 1Departments of Materials and Physics and the Thomas Young Centre for Theory and Simulation of Materials, Imperial College London, South Kensington Campus, London SW7 2AZ, United Kingdom 2Institute for Theory of Statistical Physics, RWTH Aachen University, and JARA Fundamentals of Future Information Technology, 52062 Aachen, Germany 3Max Planck Institute for the Structure and Dynamics of Matter, Center for Free Electron Laser Science, Luruper Chaussee 149, 22761 Hamburg, Germany read less NOT USED (high confidence) Z. Xiong, L. Zhong, H. Wang, and X. Li, “Structural Defects, Mechanical Behaviors, and Properties of Two-Dimensional Materials,” Materials. 2021. link Times cited: 35 Abstract: Since the success of monolayer graphene exfoliation, two-dim… read moreAbstract: Since the success of monolayer graphene exfoliation, two-dimensional (2D) materials have been extensively studied due to their unique structures and unprecedented properties. Among these fascinating studies, the most predominant focus has been on their atomic structures, defects, and mechanical behaviors and properties, which serve as the basis for the practical applications of 2D materials. In this review, we first highlight the atomic structures of various 2D materials and the structural and energy features of some common defects. We then summarize the recent advances made in experimental, computational, and theoretical studies on the mechanical properties and behaviors of 2D materials. We mainly emphasized the underlying deformation and fracture mechanisms and the influences of various defects on mechanical behaviors and properties, which boost the emergence and development of topological design and defect engineering. We also further introduce the piezoelectric and flexoelectric behaviors of specific 2D materials to address the coupling between mechanical and electronic properties in 2D materials and the interactions between 2D crystals and substrates or between different 2D monolayers in heterostructures. Finally, we provide a perspective and outlook for future studies on the mechanical behaviors and properties of 2D materials. read less NOT USED (high confidence) B. Morrow and J. Harrison, “Evaluating the Ability of Selected Force Fields to Simulate Hydrocarbons as a Function of Temperature and Pressure Using Molecular Dynamics,” Energy & Fuels. 2021. link Times cited: 4 Abstract: The ability of both nonreactive (OPLS-AA) and reactive (AIRE… read moreAbstract: The ability of both nonreactive (OPLS-AA) and reactive (AIREBO-M and ReaxFF) force fields to model pure hydrocarbon fluids at various temperatures and pressures was assessed using molecular dynamic... read less NOT USED (high confidence) J. Ewen, H. Spikes, and D. Dini, “Contributions of Molecular Dynamics Simulations to Elastohydrodynamic Lubrication,” Tribology Letters. 2021. link Times cited: 25 NOT USED (high confidence) P. Yoo, M. Sakano, S. Desai, M. M. Islam, P. Liao, and A. Strachan, “Neural network reactive force field for C, H, N, and O systems,” npj Computational Materials. 2021. link Times cited: 30 NOT USED (high confidence) T. D. Ta, H. Ta, K. Tieu, and B. Tran, “Impact of chosen force fields and applied load on thin film lubrication,” Friction. 2021. link Times cited: 0 NOT USED (high confidence) T. D. Ta, H. Ta, K. Tieu, and B. Tran, “Impact of chosen force fields and applied load on thin film lubrication,” Friction. 2021. link Times cited: 7 NOT USED (high confidence) L. Klebl, Z. A. H. Goodwin, A. Mostofi, D. Kennes, and J. Lischner, “Importance of long-ranged electron-electron interactions for the magnetic phase diagram of twisted bilayer graphene,” Physical Review B. 2020. link Times cited: 18 Abstract: Electron-electron interactions are intrinsically long-ranged… read moreAbstract: Electron-electron interactions are intrinsically long-ranged, but many models of strongly interacting electrons only take short-ranged interactions into account. Here, we present results of atomistic calculations including both long-ranged and short-ranged electron-electron interactions for the magnetic phase diagram of twisted bilayer graphene and demonstrate that qualitatively different results are obtained when long-ranged interactions are neglected. In particular, we use Hartree theory augmented with Hubbard interactions and calculate the interacting spin susceptibility at a range of doping levels and twist angles near the first magic angle to identify the dominant magnetic instabilities. At the magic angle, mostly anti-ferromagnetic order is found, while ferromagnetism dominates at other twist angles. Moreover, long-ranged interactions significantly increase the twist angle window in which strong correlation phenomena can be expected. These findings are in good agreement with available experimental data. read less NOT USED (high confidence) N. Kondratyuk, V. Pisarev, and J. Ewen, “Probing the high-pressure viscosity of hydrocarbon mixtures using molecular dynamics simulations.,” The Journal of chemical physics. 2020. link Times cited: 16 Abstract: Computational predictions of the high-pressure viscosity of … read moreAbstract: Computational predictions of the high-pressure viscosity of hydrocarbon mixtures could help to accelerate the development of fuels and lubricants with improved performance. In this study, we use molecular dynamics simulations to study the viscosity and density of methylcyclohexane, 1-methylnaphthalene, and their binary mixtures at 323 K and pressures of up to 500 MPa. The simulation results are in excellent agreement with previous experiments available up to 100 MPa for both pure compounds (200 MPa for 1-methylnaphthalene) and the binary mixtures. For 1-methylnaphthalene, the viscosity initially increases slower-than-exponential with pressure before it reaches an inflection point and then increases faster-than-exponential. The inflection point (300 MPa) occurs at a pressure slightly below the one at which 1-methylnaphthalene is expected to enter the supercooled phase (400 MPa). For methylcyclohexane, the increase in viscosity with pressure is slower-than-exponential over the entire pressure range studied. The binary mixtures show intermediate pressure-viscosity responses between the two pure cases. The applicability of equations commonly used to describe the pressure dependence of viscosity, as well as the viscosity of binary mixtures, is evaluated against the computational predictions. read less NOT USED (high confidence) H. Liu et al., “Dynamics of bond breaking and formation in polyethylene near shock front.,” Physical review. E. 2020. link Times cited: 1 Abstract: In a systematic study of shock wave propagating in crystalli… read moreAbstract: In a systematic study of shock wave propagating in crystalline polyethylenes using molecular dynamics method and the electron force field (eFF) potential, we show that microscopic structure of shock front is significantly affected by the anisotropy of long carbon chain and the bond breaking and recombination dynamics. However, macroscopic properties measured in Hugoniot experiments, such as compression ratio and shock velocity, are not sensitive to carbon chain anisotropy and bond dynamics. Our work also display that hydrogen molecules are formed when the piston speed is in the region between 10 km/s and 30 km/s. However, carbon-hydrogen pair distribution function does not display an indication of carbon-hydrogen phase segregation. read less 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) Z. E. Oufir, H. Ramézani, N. Mathieu, S. Bhatia, and S. Delpeux, “Impact of high adsorbent conductivity on adsorption of polar molecules: simulation of phenol adsorption on graphene sheets,” Adsorption. 2020. link Times cited: 5 NOT USED (high confidence) S. Signetti, K. Kang, N. Pugno, and S. Ryu, “Atomistic modelling of the hypervelocity dynamics of shock-compressed graphite and impacted graphene armours,” Computational Materials Science. 2019. link Times cited: 5 NOT USED (high confidence) L. Wang, J. Jin, P. Yang, Y. Zong, and Q. Peng, “Graphene Adhesion Mechanics on Iron Substrates: Insight from Molecular Dynamic Simulations,” Crystals. 2019. link Times cited: 8 Abstract: The adhesion feature of graphene on metal substrates is impo… read moreAbstract: The adhesion feature of graphene on metal substrates is important in graphene synthesis, transfer and applications, as well as for graphene-reinforced metal matrix composites. We investigate the adhesion energy of graphene nanosheets (GNs) on iron substrate using molecular dynamic (MD) simulations. Two Fe–C potentials are examined as Lennard–Jones (LJ) pair potential and embedded-atom method (EAM) potential. For LJ potential, the adhesion energies of monolayer GN are 0.47, 0.62, 0.70 and 0.74 J/m2 on the iron {110}, {111}, {112} and {100} surfaces, respectively, compared to the values of 26.83, 24.87, 25.13 and 25.01 J/m2 from EAM potential. When the number of GN layers increases from one to three, the adhesion energy from EAM potential increases. Such a trend is not captured by LJ potential. The iron {110} surface is the most adhesive surface for monolayer, bilayer and trilayer GNs from EAM potential. The results suggest that the LJ potential describes a weak bond of Fe–C, opposed to a hybrid chemical and strong bond from EAM potential. The average vertical distances between monolayer GN and four iron surfaces are 2.0–2.2 Å from LJ potential and 1.3–1.4 Å from EAM potential. These separations are nearly unchanged with an increasing number of layers. The ABA-stacked GN is likely to form on lower-index {110} and {100} surfaces, while the ABC-stacked GN is preferred on higher-index {111} surface. Our insights of the graphene adhesion mechanics might be beneficial in graphene growing, surface engineering and enhancement of iron using graphene sheets. read less 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) 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) C. A. Latorre, J. Ewen, C. Gattinoni, and D. Dini, “Simulating Surfactant-Iron Oxide Interfaces: From Density Functional Theory to Molecular Dynamics.,” The journal of physical chemistry. B. 2019. link Times cited: 23 Abstract: Understanding the behaviour of surfactant molecules on iron … read moreAbstract: Understanding the behaviour of surfactant molecules on iron oxide surfaces is important for many industrial applications. Molecular dynamics (MD) simulations of such systems have been limited by the absence of a force-field (FF) which accurately describes the molecule-surface interactions. In this study, interaction energies from density functional theory (DFT) + U calculations with a van der Waals functional are used to parameterize a classical FF for MD simulations of amide surfactants on iron oxide surfaces. The Original FF, which was derived using mixing rules and surface Lennard-Jones (LJ) parameters developed for nonpolar molecules, were shown to significantly underestimate the adsorption energy and overestimate the equilibrium adsorption distance compared to DFT. Conversely, the Optimized FF showed excellent agreement with the interaction energies obtained from DFT calculations for a wide range of surface coverages and molecular conformations near to and adsorbed on α-Fe2O3(0001). This was facilitated through the use of a Morse potential for strong chemisorption interactions, modified LJ parameters for weaker physisorption interactions, and adjusted partial charges for the electrostatic interactions. The Original FF and Optimized FF were compared in classical nonequilibrium molecular dynamics (NEMD) simulations of amide molecules confined between iron oxide surfaces. When the Optimized FF was employed, the amide molecules were pulled closer to the surface and the orientation of the headgroups was more similar to that observed in the DFT calculations compared to the Original FF. The Optimized FF proposed here facilitates classical MD simulations of anhydrous amide-iron oxide interfaces in which the interactions are representative of accurate DFT calculations. read less NOT USED (high confidence) M. Höhnerbach and P. Bientinesi, “Accelerating AIREBO: Navigating the Journey from Legacy to High‐Performance Code,” Journal of Computational Chemistry. 2019. link Times cited: 6 Abstract: Despite initiatives to improve the quality of scientific sof… read moreAbstract: Despite initiatives to improve the quality of scientific software, there still is a large presence of legacy code. The focus of such code is usually on domain‐science features, rather than maintainability or highest performance. Additionally, architecture specific optimizations often result in less maintainable code. In this article, we focus on the AIREBO potential from LAMMPS, which exhibits large and complex computational kernels, hindering any systematic optimization. We suggest an approach based on complexity‐reducing refactoring and hardware abstraction and present the journey from the C++ port of a previous Fortran code to performance‐portable, KNC‐hybrid, vectorized, scalable, and optimized code supporting full and reduced precision. The journey includes extensive testing that fixed bugs in the original code. Large‐scale, full‐precision runs sustain speedups of more than 4× (KNL) and 3× (Skylake). © 2019 Wiley Periodicals, Inc. read less NOT USED (high confidence) M. Veit, “Designing a machine learning potential for molecular simulation of liquid alkanes.” 2019. link Times cited: 0 Abstract: First-year training funded by the EPSRC as part of the centr… read moreAbstract: First-year training funded by the EPSRC as part of the centre for doctoral training in computational methods for materials science (CDT CMM) under grant number EP/L015552/1.
PhD studentship funding by Shell Global Solutions International B.V.
Computer time provided by ARCHER (http://archer.ac.uk) under the UKCP Consortium, EPSRC grant number EP/P022596/1. read less NOT USED (high confidence) K. Rego and V. Meunier, “Carbon nanotube knots,” AIP Advances. 2019. link Times cited: 7 Abstract: The structural and mechanical properties of carbon nanotube … read moreAbstract: The structural and mechanical properties of carbon nanotube knots are investigated using molecular dynamics simulations. Using parametric representations of mathematical (harmonic) knots, a method is provided for calculating the initial atomic coordinates of carbon nanotubes in the shape of arbitrary knots for use in molecular dynamics simulations. A computational stress-strain testing scheme is implemented and applied to (5, 5) knotted carbon nanotubes to determine their tensile strength, plastic limit, and relative knot strength. Stress-strain curves are given for (5, 5) carbon nanotube stopper knots. It is determined that a carbon nanotube’s tensile strength is reduced to at most 1/3 of its original strength when tied into a knot. It is also shown that it is possible to form tight and stable carbon nanotube knots by subjecting the knots to stress beyond the plastic limit. In contrast, loose knots stabilized by noncovalent interactions are not dynamically stable and spontaneously untie. To help understand the stability of loose carbon nanotube knots, the relationship between bending strain energy and curvature is studied using carbon tori. Our study demonstrates the possibility to tie carbon nanotubes into various stable knots and provides a general framework for the study of other macromolecular knots relevant to potentially useful nanotechnology.The structural and mechanical properties of carbon nanotube knots are investigated using molecular dynamics simulations. Using parametric representations of mathematical (harmonic) knots, a method is provided for calculating the initial atomic coordinates of carbon nanotubes in the shape of arbitrary knots for use in molecular dynamics simulations. A computational stress-strain testing scheme is implemented and applied to (5, 5) knotted carbon nanotubes to determine their tensile strength, plastic limit, and relative knot strength. Stress-strain curves are given for (5, 5) carbon nanotube stopper knots. It is determined that a carbon nanotube’s tensile strength is reduced to at most 1/3 of its original strength when tied into a knot. It is also shown that it is possible to form tight and stable carbon nanotube knots by subjecting the knots to stress beyond the plastic limit. In contrast, loose knots stabilized by noncovalent interactions are not dynamically stable and spontaneously untie. To help understa... read less NOT USED (high confidence) E. Yakub, “Role of short-range atom-atom forces in formation of the orientational structure of simple molecular crystals,” Low Temperature Physics. 2019. link Times cited: 1 Abstract: An attempt is made to explain the appearance of certain phas… read moreAbstract: An attempt is made to explain the appearance of certain phases having different orientational and spatial structures in the phase diagram of crystals formed by tetrahedral molecules. The classical Monte Carlo method is applied to solid heavy methane CD4 and the role of various contributions to the non-central intermolecular interactions in formation of the orientational structure in simple molecular crystals is assessed. read less 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) 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 NOT USED (high confidence) J. Krajniak, Z. Zhang, S. Pandiyan, E. Nies, and G. Samaey, “Coarse‐grained molecular dynamics simulations of polymerization with forward and backward reactions,” Journal of Computational Chemistry. 2018. link Times cited: 11 Abstract: We develop novel parallel algorithms that allow molecular dy… read moreAbstract: We develop novel parallel algorithms that allow molecular dynamics simulations in which byproduct molecules are created and removed because of the chemical reactions during the molecular dynamics simulation. To prevent large increases in the potential energy, we introduce the byproduct molecules smoothly by changing the non‐bonded interactions gradually. To simulate complete equilibrium reactions, we allow the byproduct molecules attack and destroy created bonds. Modeling of such reactions are, for instance, important to study the pore formation due to the presence of e.g. water molecules or development of polymer morphology during the process of splitting off byproduct molecules. Another concept that could be studied is the degradation of polymeric materials, a very important topic in a recycling of polymer waste. We illustrate the method by simulating the polymerization of polyethylene terephthalate (PET) at the coarse‐grained level as an example of a polycondensation reaction with water as a byproduct. The algorithms are implemented in a publicly available software package and are easily accessible using a domain‐specific language that describes chemical reactions in an input configuration file. © 2018 Wiley Periodicals, Inc. read less NOT USED (high confidence) N. Filla, R. Ramasamy, and X. Wang, “Forces, energetics, and dynamics of conjugated-carbon ring tethers adhered to CNTs: a computational investigation.,” Physical chemistry chemical physics : PCCP. 2018. link Times cited: 2 Abstract: The strength and nature of the interactions between carbon n… read moreAbstract: The strength and nature of the interactions between carbon nanotubes (CNTs) and molecular tethers plays a vital role in technology such as CNT-enzyme sensors. Tethers that attach noncovalently to CNTs are ideal for retaining the electrical properties of the CNTs since they do not degrade the CNT surface and effect its electrical conductivity. However, leaching due to weak CNT-tether attachment is very common when using noncovalent tethers, and this has limited their use in commercial products including biosensors. Thus, understanding the fundamental mechanics governing the strength of CNT-tether adhesion is crucial for the design of highly sensitive, viable sensors. Here, we computationally investigate the adhesion strength of CNT-tether complexes with 8 different tethering molecules designed to adhere noncovalently to the CNT surface. We study the effects of CNT diameter, CNT chirality, and the size/geometry of the tethering molecule on the adhesion energy and force. Our results show an asymptotic relationship between adhesion strength and CNT diameter. Calculations show that noncovalent tethers tested here can reach adhesion forces and energies that are up to 21% and 54% of the strength of the carbon-carbon single bond force and bond energy respectively. We anticipate our results will help guide CNT-enzyme sensor design to produce sensors with high sensitivity and minimal leaching. read less NOT USED (high confidence) M. Z. Hossain, T. Hao, and B. Silverman, “Stillinger–Weber potential for elastic and fracture properties in graphene and carbon nanotubes,” Journal of Physics: Condensed Matter. 2018. link Times cited: 42 Abstract: This paper presents a new framework for determining the Stil… read moreAbstract: This paper presents a new framework for determining the Stillinger–Weber (SW) potential parameters for modeling fracture in graphene and carbon nanotubes. In addition to fitting the equilibrium material properties, the approach allows fitting the potential to the forcing behavior as well as the mechanical strength of the solid, without requiring ad hoc modification of the nearest-neighbor interactions for avoiding artificial stiffening of the lattice at larger deformation. Consistent with the first-principles results, the potential shows the Young’s modulus of graphene to be isotropic under symmetry-preserving and symmetry-breaking deformation conditions. It also shows the Young’s modulus of carbon nanotubes to be diameter-dependent under symmetry-breaking loading conditions. The potential addresses the key deficiency of existing empirical potentials in reproducing experimentally observed glass-like brittle fracture in graphene and carbon nanotubes. In simulating the entire deformation process leading to fracture, the SW-potential costs several factors less computational time compared to the state-of-the-art interatomic potentials that enables exploration of the fracture processes in large atomistic systems which are inaccessible otherwise. read less NOT USED (high confidence) S. Hu, W.-guo Sun, J. Fu, Z. Zhang, W. Wu, and Y. Tang, “Initiation mechanisms and kinetic analysis of the isothermal decomposition of poly(α-methylstyrene): a ReaxFF molecular dynamics study,” RSC Advances. 2018. link Times cited: 11 Abstract: This study investigates the thermal decomposition initiation… read moreAbstract: This study investigates the thermal decomposition initiation mechanisms and kinetics of poly(α-methylstyrene) (PαMS) under isothermal conditions, using molecular dynamics simulations with the ReaxFF reactive force field. The unimolecular pyrolysis simulations show that the thermal decomposition of the PαMS molecule is initiated mainly by carbon–carbon backbone cleavage in two types at random points along the main chain that leads to different intermediates, and is accompanied by depolymerization reactions that lead to the formation of the final products. The time evolution of typical species in the process of PαMS thermal decomposition at various temperatures presents specific evolution profiles and shows a temperature-dependence effect. Isothermal decomposition kinetic analysis based on PαMS pyrolysis shows that the activation energy varies with the degree of conversion during the thermal decomposition processes, which infers that the decomposition process at different conversions may have different reaction mechanisms. read less NOT USED (high confidence) Q. Xu, X. Li, J. Zhang, Y.-zhong Hu, H. Wang, and T. Ma, “Suppressing Nanoscale Wear by Graphene/Graphene Interfacial Contact Architecture: A Molecular Dynamics Study.,” ACS applied materials & interfaces. 2017. link Times cited: 39 Abstract: Nanoscale wear is one of the key factors hindering the perfo… read moreAbstract: Nanoscale wear is one of the key factors hindering the performance and lifetime of micro- and nanosystems, such as the scanning tip wear in atomic force microscopy (AFM), the head-disk interface in magnetic storage system, and the moving components in micro- or nanoelectromechanical systems (MEMS/NEMS). Here, we propose to construct the graphene/graphene interfacial architecture to suppress the nanoscale wear. Molecular dynamics simulations show that the atomic roughness of the sliding surfaces with either stepped or amorphous structure can lead to strong inhomogeneity of the local contact pressure distribution. By coating graphene on both sides of the frictional surfaces, the local contact pressure fluctuations due to the atomic roughness are suppressed. Moreover, this trend is more evident with the increasing layer number of the graphene coating. Furthermore, the nanoscratching simulation suggests that the rupture of graphene is driven by the inhomogeneous pressure distribution-induced lateral atomic interlocking between the rough tip and substrate and the consequent in-plane lattice deformation and C-C bond breaking during sliding. By coating graphene on the rough amorphous carbon tip, the critical normal load for wear failure of graphene is significantly increased, due to the weakening effect of the atomic interlocking by improving the contact conditions with atomically smooth graphene/graphene sliding interface. This investigation reveals a strategy for reducing nanowear by suppressing the local contact pressure fluctuations via graphene/graphene sliding interface architecture, which provides a theoretical guidance for designing wear-resistant coatings for the longevity of AFM probes and MEMS/NEMS systems. read less NOT 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 NOT USED (high confidence) S.-H. Kim et al., “Harvesting electrical energy from carbon nanotube yarn twist,” Science. 2017. link Times cited: 265 Abstract: Making the most of twists and turns The rise of small-scale,… read moreAbstract: Making the most of twists and turns The rise of small-scale, portable electronics and wearable devices has boosted the desire for ways to harvest energy from mechanical motion. Such approaches could be used to provide battery-free power with a small footprint. Kim et al. present an energy harvester made from carbon nanotube yarn that converts mechanical energy into electrical energy from both torsional and tensile motion. Their findings reveal how the extent of yarn twisting and the combination of homochiral and heterochiral coiled yarns can maximize energy generation. Science, this issue p. 773 Twisted and coiled carbon nanotubes can harvest electrical energy from mechanical motion. Mechanical energy harvesters are needed for diverse applications, including self-powered wireless sensors, structural and human health monitoring systems, and the extraction of energy from ocean waves. We report carbon nanotube yarn harvesters that electrochemically convert tensile or torsional mechanical energy into electrical energy without requiring an external bias voltage. Stretching coiled yarns generated 250 watts per kilogram of peak electrical power when cycled up to 30 hertz, as well as up to 41.2 joules per kilogram of electrical energy per mechanical cycle, when normalized to harvester yarn weight. These energy harvesters were used in the ocean to harvest wave energy, combined with thermally driven artificial muscles to convert temperature fluctuations to electrical energy, sewn into textiles for use as self-powered respiration sensors, and used to power a light-emitting diode and to charge a storage capacitor. read less NOT USED (definite) K. Mustonen et al., “Atomic-Scale Deformations at the Interface of a Mixed-Dimensional van der Waals Heterostructure,” ACS Nano. 2018. link Times cited: 20 Abstract: Molecular self-assembly due to chemical interactions is the … read moreAbstract: Molecular self-assembly due to chemical interactions is the basis of bottom-up nanofabrication, whereas weaker intermolecular forces dominate on the scale of macromolecules. Recent advances in synthesis and characterization have brought increasing attention to two- and mixed-dimensional heterostructures, and it has been recognized that van der Waals (vdW) forces within the structure may have a significant impact on their morphology. Here, we suspend single-walled carbon nanotubes (SWCNTs) on graphene to create a model system for the study of a 1D–2D molecular interface through atomic-resolution scanning transmission electron microscopy observations. When brought into contact, the radial deformation of SWCNTs and the emergence of long-range linear grooves in graphene revealed by the three-dimensional reconstruction of the heterostructure are observed. These topographic features are strain-correlated but show no sensitivity to carbon nanotube helicity, electronic structure, or stacking order. Finally, despite the random deposition of the nanotubes, we show that the competition between strain and vdW forces results in aligned carbon–carbon interfaces spanning hundreds of nanometers. read less |
