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Jinwu Jiang - One of the best experts on this subject based on the ideXlab platform.
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Parameterization of Stillinger-Weber Potential for Two- Dimensional Atomic Crystals
Handbook of Stillinger-Weber Potential Parameters for Two-Dimensional Atomic Crystals, 2017Co-Authors: Jinwu Jiang, Yu-ping ZhouAbstract:We parametrize the Stillinger-Weber potential for 156 two-dimensional atomic crystals. Parameters for the Stillinger-Weber potential are obtained from the valence force field model following the analytic approach (Nanotechnology 26, 315706 (2015)), in which the valence force constants are determined by the phonon spectrum. The Stillinger-Weber potential is an efficient nonlinear interaction, and is applicable for numerical simulations of nonlinear physical or mechanical processes. The supplemental resources for all simulations in the present work are available online in Ref. 1, including a fortran code to generate crystals' structures, files for molecular dynamics simulations using LAMMPS, files for phonon calculations with the Stillinger-Weber potential using GULP, and files for phonon calculations with the valence force field model using GULP.
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Molecular dynamics simulations for mechanical properties of borophene: parameterization of valence force field model and Stillinger-Weber potential.
Scientific reports, 2017Co-Authors: Yu-ping Zhou, Jinwu JiangAbstract:While most existing theoretical studies on the borophene are based on first-principles calculations, the present work presents molecular dynamics simulations for the lattice dynamical and mechanical properties in borophene. The obtained mechanical quantities are in good agreement with previous first-principles calculations. The key ingredients for these molecular dynamics simulations are the two efficient empirical potentials developed in the present work for the interaction of borophene with low-energy triangular structure. The first one is the valence force field model, which is developed with the assistance of the phonon dispersion of borophene. The valence force field model is a linear potential, so it is rather efficient for the calculation of linear quantities in borophene. The second one is the Stillinger-Weber potential, whose parameters are derived based on the valence force field model. The Stillinger-Weber potential is applicable in molecular dynamics simulations of nonlinear physical or mechanical quantities in borophene.
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parametrization of Stillinger weber potential based on valence force field model application to single layer mos2 and black phosphorus
Nanotechnology, 2015Co-Authors: Jinwu JiangAbstract:We propose parametrizing the Stillinger-Weber potential for covalent materials starting from the valence force-field model. All geometrical parameters in the Stillinger-Weber potential are determined analytically according to the equilibrium condition for each individual potential term, while the energy parameters are derived from the valence force-field model. This parametrization approach transfers the accuracy of the valence force field model to the Stillinger-Weber potential. Furthermore, the resulting Stilliinger-Weber potential supports stable molecular dynamics simulations, as each potential term is at an energy-minimum state separately at the equilibrium configuration. We employ this procedure to parametrize Stillinger-Weber potentials for single-layer MoS2 and black phosphorous. The obtained Stillinger-Weber potentials predict an accurate phonon spectrum and mechanical behaviors. We also provide input scripts of these Stillinger-Weber potentials used by publicly available simulation packages including GULP and LAMMPS.
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parametrization of Stillinger weber potential based on valence force field model application to single layer mos2 and black phosphorus
arXiv: Materials Science, 2015Co-Authors: Jinwu JiangAbstract:We propose to parametrize the Stillinger-Weber potential for covalent materials starting from the valence force field model. All geometrical parameters in the Stillinger-Weber potential are determined analytically according to the equilibrium condition for each individual potential term, while the energy parameters are derived from the valence force field model. This parametrization approach transfers the accuracy of the valence force field model to the Stillinger-Weber potential. Furthermore, the resulting Stilliinger-Weber potential supports for stable molecular dynamics simulations, as each potential term is at energy minimum state separately at the equilibrium configuration. We employ this procedure to parametrize Stillinger-Weber potentials for the single-layer MoS2 and black phosphorous. The obtained Stillinger-Weber potentials predict accurate phonon spectrum and mechanical behaviors. We also provide input scripts of these Stillinger-Weber potentials used by publicly available simulation packages including GULP and LAMMPS.
Pankaj A Apte - One of the best experts on this subject based on the ideXlab platform.
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Nonmonotonic Dependence of the Absolute Entropy on Temperature in Supercooled Stillinger-Weber Silicon
Journal of Statistical Physics, 2012Co-Authors: Pankaj A Apte, Arvind K. GautamAbstract:Using a recently developed thermodynamic integration method, we compute the precise values of the excess Gibbs free energy ( G ^ e ) of the high density liquid (HDL) phase with respect to the crystalline phase at different temperatures ( T ) in the supercooled region of the Stillinger-Weber (SW) silicon (Stillinger and Weber in Phys. Rev. B 31:5262–5271, 1985 ). Based on the slope of G ^ e with respect to T , we find that the absolute entropy of the HDL phase increases as its enthalpy changes from the equilibrium value at T ≥1065 K to the value corresponding to a non-equilibrium state at 1060 K. We find that the volume distribution in the equilibrium HDL phases become progressively broader as the temperature is reduced to 1060 K, exhibiting van-der-Waals (VDW) loop in the pressure-volume curves. Our results provides insight into the thermodynamic cause of the transition from the HDL phase to the low density phases in SW silicon, observed in earlier studies near 1060 K at zero pressure.
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Nonmonotonic dependence of the absolute entropy on temperature in supercooled Stillinger-Weber silicon
Journal of Statistical Physics, 2012Co-Authors: Pankaj A Apte, Arvind K. GautamAbstract:Using a recently developed thermodynamic integration method, we compute the precise values of the excess Gibbs free energy (G^e) of the high density liquid (HDL) phase with respect to the crystalline phase at different temperatures (T) in the supercooled region of the Stillinger-Weber (SW) silicon [F. H. Stillinger and T. A. Weber, Phys. Rev. B. 32, 5262 (1985)]. Based on the slope of G^e with respect to T, we find that the absolute entropy of the HDL phase increases as its enthalpy changes from the equilibrium value at T \ge 1065 K to the value corresponding to a non-equilibrium state at 1060 K. We find that the volume distribution in the equilibrium HDL phases become progressively broader as the temperature is reduced to 1060 K, exhibiting van-der-Waals (VDW) loop in the pressure-volume curves. Our results provides insight into the thermodynamic cause of the transition from the HDL phase to the low density phases in SW silicon, observed in earlier studies near 1060 K at zero pressure.
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anisotropy of crystal melt interfacial free energy of silicon by simulation
Applied Physics Letters, 2008Co-Authors: Pankaj A Apte, Xiao Cheng ZengAbstract:We extend the cleaving wall method to a nonpairwise additive potential. Using this method, we compute the anisotropy of crystal-melt interfacial free energy γ for Stillinger–Weber potential of silicon [F. H. Stillinger and T. A. Weber, Phys. Rev. B 31, 5262 (1985)]. The calculated γ for (100), (111), and (110) orientations are 0.42±0.02, 0.34±0.02, and 0.35±0.03J∕m2, respectively. The anisotropy in γ we found is consistent with the experimental observation that Si(100)-melt interface develops (111) facets and also helps in explaining a higher undercooling observed for Si(111)-melt interface in Czochralski method.
R. E. Jones - One of the best experts on this subject based on the ideXlab platform.
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A Stillinger-Weber Potential for InGaN
Journal of Materials Science Research, 2017Co-Authors: X. W. Zhou, R. E. JonesAbstract:Reducing defects in InGaN films deposited on GaN substrates has been critical to fill the “green” gap for solid-state lighting applications. To enable researchers to use molecular dynamics vapor deposition simulations to explores ways to reduce defects in InGaN films, we have developed and characterized a Stillinger-Weber potential for InGaN. We show that this potential reproduces the experimental atomic volume, cohesive energy, and bulk modulus of the equilibrium wurtzite / zinc-blende phases of both InN and GaN. Most importantly, the potential captures the stability of the correct phase of InGaN compounds against a variety of other elemental, alloy, and compound configurations. This is validated by the potential’s ability to predict crystalline growth of stoichiometric wurtzite and zinc-blende InxGa1-xN compounds during vapor deposition simulations where adatoms are randomly injected to the growth surface.
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Effects of cutoff functions of Tersoff potentials on molecular dynamics simulations of thermal transport
Modelling and Simulation in Materials Science and Engineering, 2011Co-Authors: X. W. Zhou, R. E. JonesAbstract:Past molecular dynamics studies of thermal transport have predominantly used Stillinger–Weber potentials. As materials continuously shrink, their properties increasingly depend on defect and surface effects. Unfortunately, Stillinger–Weber potentials are best used for diamond-cubic-like bulk crystals. They cannot represent the energies of many metastable phases, nor can they accurately predict the energetics of defective and surface regions. To study nanostructured materials, where these regions can dominate thermal transport, the accuracy of Tersoff potentials in representing these structures is more desirable. Based upon an analysis of thermal transport in a GaN system, we demonstrate that the cutoff function of the existing Tersoff potentials may lead to problems in determining the thermal conductivity. To remedy this issue, improved cutoff schemes are proposed and evaluated.
X. W. Zhou - One of the best experts on this subject based on the ideXlab platform.
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A Stillinger-Weber Potential for InGaN
Journal of Materials Science Research, 2017Co-Authors: X. W. Zhou, R. E. JonesAbstract:Reducing defects in InGaN films deposited on GaN substrates has been critical to fill the “green” gap for solid-state lighting applications. To enable researchers to use molecular dynamics vapor deposition simulations to explores ways to reduce defects in InGaN films, we have developed and characterized a Stillinger-Weber potential for InGaN. We show that this potential reproduces the experimental atomic volume, cohesive energy, and bulk modulus of the equilibrium wurtzite / zinc-blende phases of both InN and GaN. Most importantly, the potential captures the stability of the correct phase of InGaN compounds against a variety of other elemental, alloy, and compound configurations. This is validated by the potential’s ability to predict crystalline growth of stoichiometric wurtzite and zinc-blende InxGa1-xN compounds during vapor deposition simulations where adatoms are randomly injected to the growth surface.
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A modified Stillinger-Weber potential for TlBr and its polymorphic extension
Journal of Materials Science Research, 2015Co-Authors: X. W. Zhou, Reese E. Jones, Michael E. Foster, Pin Yang, Hongyou Fan, F. P. DotyAbstract:TlBr is promising for g- and x- radiation detection, but suffers from rapid performance degradation under the operating external electric fields. To enable molecular dynamics (MD) studies of this degradation, we have developed a Stillinger-Weber type of TlBr interatomic potential. During this process, we have also addressed two problems of wider interests. First, the conventional Stillinger-Weber potential format is only applicable for tetrahedral structures (e.g., diamond-cubic, zinc-blende, or wurtzite). Here we have modified the analytical functions of the Stillinger-Weber potential so that it can now be used for other crystal structures. Second, past modifications of interatomic potentials cannot always be applied by a broad community because any new analytical functions of the potential would require corresponding changes in the molecular dynamics codes. Here we have developed a polymorphic potential model that simultaneously incorporates Stillinger-Weber, Tersoff, embedded-atom method, and any variations (i.e., modified functions) of these potentials. We have implemented this polymorphic model in MD code LAMMPS, and demonstrated that our TlBr potential enables stable MD simulations under external electric fields.
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Effects of cutoff functions of Tersoff potentials on molecular dynamics simulations of thermal transport
Modelling and Simulation in Materials Science and Engineering, 2011Co-Authors: X. W. Zhou, R. E. JonesAbstract:Past molecular dynamics studies of thermal transport have predominantly used Stillinger–Weber potentials. As materials continuously shrink, their properties increasingly depend on defect and surface effects. Unfortunately, Stillinger–Weber potentials are best used for diamond-cubic-like bulk crystals. They cannot represent the energies of many metastable phases, nor can they accurately predict the energetics of defective and surface regions. To study nanostructured materials, where these regions can dominate thermal transport, the accuracy of Tersoff potentials in representing these structures is more desirable. Based upon an analysis of thermal transport in a GaN system, we demonstrate that the cutoff function of the existing Tersoff potentials may lead to problems in determining the thermal conductivity. To remedy this issue, improved cutoff schemes are proposed and evaluated.
Francesco Sciortino - One of the best experts on this subject based on the ideXlab platform.
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Physics of the Liquid-Liquid Critical Point
Physical review letters, 2003Co-Authors: Francesco Sciortino, Emilia La Nave, Piero TartagliaAbstract:Within the inherent structure thermodynamic formalism introduced by Stillinger and Weber [F. H. Stillinger and T. A. Weber, Phys. Rev. A 25, 978 (1982)], we address the basic question of the physics of the liquid-liquid transition and of density maxima observed in some complex liquids such as water by identifying, for the first time, the statistical properties of the potential energy landscape responsible for these anomalies. We also provide evidence of the connection between density anomalies and the liquid-liquid critical point. Within the simple (and physically transparent) model discussed, density anomalies do imply the existence of a liquid-liquid transition.
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Equation of state of supercooled water from the sedimentation profile.
Physical review. E Statistical nonlinear and soft matter physics, 2003Co-Authors: Masako Yamada, H. Eugene Stanley, Francesco SciortinoAbstract:To study the coexistence of two liquid states of water within one simulation box, we implement an equilibrium sedimentation method--which involves applying a gravitational field to the system and measuring or calculating the resulting density profile in equilibrium. We simulate a system of particles interacting via the Stillinger-2 (ST2) potential, a model for water. We detect the coexistence of two liquid phases at low temperature.
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Potential energy landscape equation of state.
Physical review letters, 2002Co-Authors: Emilia La Nave, Stefano Mossa, Francesco SciortinoAbstract:Depth, number, and shape of the basins of the potential energy landscape are the key ingredients of the inherent structure thermodynamic formalism introduced by Stillinger and Weber [F. H. Stillinger and T. A. Weber, Phys. Rev. A 25, 978 (1982)]. Within this formalism, an equation of state based only on the volume dependence of these landscape properties is derived. Vibrational and configurational contributions to pressure are sorted out in a transparent way. Predictions are successfully compared with data from extensive molecular dynamics simulations of a simple model for the fragile liquid orthoterphenyl.