× Updated! Potentials that share interactions are now listed as related models.
 
Citation: M. Wen, and E.B. Tadmor (2020), "Uncertainty quantification in molecular simulations with dropout neural network potentials", npj Computational Materials, 6(1), 124. DOI: 10.1038/s41524-020-00390-8.
Abstract: Machine learning interatomic potentials (IPs) can provide accuracy close to that of first-principles methods, such as density functional theory (DFT), at a fraction of the computational cost. This greatly extends the scope of accurate molecular simulations, providing opportunities for quantitative design of materials and devices on scales hitherto unreachable by DFT methods. However, machine learning IPs have a basic limitation in that they lack a physical model for the phenomena being predicted and therefore have unknown accuracy when extrapolating outside their training set. In this paper, we propose a class of Dropout Uncertainty Neural Network (DUNN) potentials that provide rigorous uncertainty estimates that can be understood from both Bayesian and frequentist statistics perspectives. As an example, we develop a DUNN potential for carbon and show how it can be used to predict uncertainty for static and dynamical properties, including stress and phonon dispersion in graphene. We demonstrate two approaches to propagate uncertainty in the potential energy and atomic forces to predicted properties. In addition, we show that DUNN uncertainty estimates can be used to detect configurations outside the training set, and in some cases, can serve as a predictor for the accuracy of a calculation.

Notes: This is the version of the DUNN potential that uses a dropout ratio of 0.1.

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Notes: Listing found at https://openkim.org.
Link(s):
Citation: M. Wen, and E.B. Tadmor (2020), "Uncertainty quantification in molecular simulations with dropout neural network potentials", npj Computational Materials, 6(1), 124. DOI: 10.1038/s41524-020-00390-8.
Abstract: Machine learning interatomic potentials (IPs) can provide accuracy close to that of first-principles methods, such as density functional theory (DFT), at a fraction of the computational cost. This greatly extends the scope of accurate molecular simulations, providing opportunities for quantitative design of materials and devices on scales hitherto unreachable by DFT methods. However, machine learning IPs have a basic limitation in that they lack a physical model for the phenomena being predicted and therefore have unknown accuracy when extrapolating outside their training set. In this paper, we propose a class of Dropout Uncertainty Neural Network (DUNN) potentials that provide rigorous uncertainty estimates that can be understood from both Bayesian and frequentist statistics perspectives. As an example, we develop a DUNN potential for carbon and show how it can be used to predict uncertainty for static and dynamical properties, including stress and phonon dispersion in graphene. We demonstrate two approaches to propagate uncertainty in the potential energy and atomic forces to predicted properties. In addition, we show that DUNN uncertainty estimates can be used to detect configurations outside the training set, and in some cases, can serve as a predictor for the accuracy of a calculation.

Notes: This is the version of the DUNN potential that uses a dropout ratio of 0.2.

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Notes: Listing found at https://openkim.org.
Link(s):
Citation: M. Wen, and E.B. Tadmor (2020), "Uncertainty quantification in molecular simulations with dropout neural network potentials", npj Computational Materials, 6(1), 124. DOI: 10.1038/s41524-020-00390-8.
Abstract: Machine learning interatomic potentials (IPs) can provide accuracy close to that of first-principles methods, such as density functional theory (DFT), at a fraction of the computational cost. This greatly extends the scope of accurate molecular simulations, providing opportunities for quantitative design of materials and devices on scales hitherto unreachable by DFT methods. However, machine learning IPs have a basic limitation in that they lack a physical model for the phenomena being predicted and therefore have unknown accuracy when extrapolating outside their training set. In this paper, we propose a class of Dropout Uncertainty Neural Network (DUNN) potentials that provide rigorous uncertainty estimates that can be understood from both Bayesian and frequentist statistics perspectives. As an example, we develop a DUNN potential for carbon and show how it can be used to predict uncertainty for static and dynamical properties, including stress and phonon dispersion in graphene. We demonstrate two approaches to propagate uncertainty in the potential energy and atomic forces to predicted properties. In addition, we show that DUNN uncertainty estimates can be used to detect configurations outside the training set, and in some cases, can serve as a predictor for the accuracy of a calculation.

Notes: This is the version of the DUNN potential that uses a dropout ratio of 0.3.

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Notes: Listing found at https://openkim.org.
Link(s):
Citation: M. Wen, and E.B. Tadmor (2019), "Hybrid neural network potential for multilayer graphene", Physical Review B, 100(19), 195419. DOI: 10.1103/physrevb.100.195419.
Abstract: 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 an interatomic potential for multilayer graphene structures referred to as “hNN−Grx.” 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 https://openkim.org.

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Notes: Listing found at https://openkim.org.
Link(s):
Citation: R.S. Elliott, and A. Akerson (2015), "Efficient "universal" shifted Lennard-Jones model for all KIM API supported species".

Notes: This is the C interaction from the "Universal" parameterization for the openKIM LennardJones612 model driver.The parameterization uses a shifted cutoff so that all interactions have a continuous energy function at the cutoff radius. This model was automatically fit using Lorentz-Berthelotmixing rules. It reproduces the dimer equilibrium separation (covalent radii) and the bond dissociation energies. It has not been fitted to other physical properties and its ability to model structures other than dimers is unknown. See the README and params files on the KIM model page for more details.

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Notes: Listing found at https://openkim.org.
Link(s):
Citation: X.W. Zhou, D.K. Ward, and M.E. Foster (2015), "An analytical bond-order potential for carbon", Journal of Computational Chemistry, 36(23), 1719-1735. DOI: 10.1002/jcc.23949.
Abstract: Carbon is the most widely studied material today because it exhibits special properties not seen in any other materials when in nano dimensions such as nanotube and graphene. Reduction of material defects created during synthesis has become critical to realize the full potential of carbon structures. Molecular dynamics (MD) simulations, in principle, allow defect formation mechanisms to be studied with high fidelity, and can, therefore, help guide experiments for defect reduction. Such MD simulations must satisfy a set of stringent requirements. First, they must employ an interatomic potential formalism that is transferable to a variety of carbon structures. Second, the potential needs to be appropriately parameterized to capture the property trends of important carbon structures, in particular, diamond, graphite, graphene, and nanotubes. Most importantly, the potential must predict the crystalline growth of the correct phases during direct MD simulations of synthesis to achieve a predictive simulation of defect formation. Because an unlimited number of structures not included in the potential parameterization are encountered, the literature carbon potentials are often not sufficient for growth simulations. We have developed an analytical bond order potential for carbon, and have made it available through the public MD simulation package LAMMPS. We demonstrate that our potential reasonably captures the property trends of important carbon phases. Stringent MD simulations convincingly show that our potential accounts not only for the crystalline growth of graphene, graphite, and carbon nanotubes but also for the transformation of graphite to diamond at high pressure.

LAMMPS pair_style bop (2015--Zhou-X-W--C--LAMMPS--ipr1)
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Notes: This file was taken from the August 22, 2018 LAMMPS distribution and listed as having been created by X.W. Zhou (Sandia)
File(s):
Citation: B.-J. Lee, and J.W. Lee (2005), "A modified embedded atom method interatomic potential for carbon", Calphad, 29(1), 7-16. DOI: 10.1016/j.calphad.2005.02.003.
Abstract: A semi-empirical interatomic potential for carbon has been developed, based on the modified embedded atom method formalism. The potential describes the structural properties of various polytypes of carbon, elastic, defect and surface properties of diamonds as satisfactorily as the well-known Tersoff potential. Combined with the Lennard-Jones potential, it can also reproduce the physical properties of graphite and amorphous carbon reasonably well. The applicability of the present potential to atomistic approaches on carbon nanotubes and fullerenes is also shown. The potential has the same formalism as previously developed MEAM potentials for bcc, fcc and hcp elements, and can be easily extended to describe various metal–carbon alloy systems.

LAMMPS pair_style meam (2005--Lee-B-J--C--LAMMPS--ipr1)
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Notes: These potential files were obtained from http://cmse.postech.ac.kr/home_2nnmeam, accessed Nov 9, 2020.
File(s):
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Notes: Listing found at https://openkim.org.
Link(s):
Citation: J.H. Los, and A. Fasolino (2003), "Intrinsic long-range bond-order potential for carbon: Performance in Monte Carlo simulations of graphitization", Physical Review B, 68(2), 024107. DOI: 10.1103/physrevb.68.024107.
Abstract: We propose a bond order potential for carbon with built-in long-range interactions. The potential is defined as the sum of an angular and coordination dependent short-range part accounting for the strong covalent interactions and a radial long-range part describing the weak interactions responsible, e.g., for the interplanar binding in graphite. The short-range part is a Brenner type of potential, with several modifications introduced to get an improved description of elastic properties and conjugation. Contrary to previous long-range extensions of existing bond order potentials, we prevent the loss of accuracy by compensating for the additional long-range interactions by an appropriate parametrization of the short-range part. We also provide a short-range bond order potential. In Monte Carlo simulations our potential gives a good description of the diamond to graphite transformation. For thin (111) slabs graphitization proceeds perpendicular to the surface as found in ab initio simulations, whereas for thick layers we find that graphitization occurs layer by layer.

LAMMPS pair_style lcbop (2003--Los-J-H--C--LAMMPS--ipr1)
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Notes: This file was taken from the August 22, 2018 LAMMPS distribution. The LAMMPS documentation for pair_style lcbop notes "The parameters/coefficients for the LCBOP potential as applied to C are listed in the C.lcbop file to agree with the original (Los and Fasolino) paper. Thus the parameters are specific to this potential and the way it was fit, so modifying the file should be done carefully."
File(s):
Citation: K.E. Khor, and S. Das Sarma (1988), "Proposed universal interatomic potential for elemental tetrahedrally bonded semiconductors", Physical Review B, 38(5), 3318-3322. DOI: 10.1103/physrevb.38.3318.
Abstract: Based on the idea that bonding energies of many substances can be modeled by pairwise interactions moderated by the local environment, we propose a new universal interatomic potential for tetrahedrally bonded materials. We obtain two basic relationships linking equilibrium interatomic distances and cohesive energies to the coordination number for a large range of phases of silicon. The relationships are also valid for germanium and carbon, covering, in the latter case, double and triple carbon-carbon bonds, where π bonding is important. Based on these ideas we discuss the construction of the universal interatomic potential for these three substances. This potential, which uses very few parameters, should be useful, particularly for surface studies.

Citation: J. Tersoff (1988), "Empirical Interatomic Potential for Carbon, with Applications to Amorphous Carbon", Physical Review Letters, 61(25), 2879-2882. DOI: 10.1103/physrevlett.61.2879.
Abstract: An empirical interatomic potential is introduced, which gives a convenient and relatively accurate description of the structural properties and energetics of carbon, including elastic properties, phonons, polytypes, and defects and migration barriers in diamond and graphite. The potential is applied to study amorphous carbon formed in three different ways. Two resulting structures are similar to experimental a−C, but another more diamondlike form has essentially identical energy. The liquid is also found to have unexpected properties.

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Notes: Listing found at https://openkim.org.
Link(s):
 
Citation: G. Plummer, H. Rathod, A. Srivastava, M. Radovic, T. Ouisse, M. Yildizhan, P.O. Persson, K. Lambrinou, M.W. Barsoum, and G.J. Tucker (2021), "On the origin of kinking in layered crystalline solids", Materials Today, 43, 45-52. DOI: 10.1016/j.mattod.2020.11.014.
Abstract: Kinking is a deformation mechanism ubiquitous to layered systems, ranging from the nanometer scale in layered crystalline solids, to the kilometer scale in geological formations. Herein, we demonstrate its origins in the former through multiscale experiments and atomistic simulations. When compressively loaded parallel to their basal planes, layered crystalline solids first buckle elastically, then nucleate atomic-scale, highly stressed ripplocation boundaries – a process driven by redistributing strain from energetically expensive in-plane bonds to cheaper out-of-plane bonds. The consequences are far reaching as the unique mechanical properties of layered crystalline solids are highly dependent upon their ability to deform by kinking. Moreover, the compressive strength of numerous natural and engineered layered systems depends upon the ease of kinking or lack there of.

Notes: This potential was designed for studies of MAX phase deformation, with particular attention paid to replicating the characteristics of basal slip. It successfully captures MAX phase plastic anisotropy, predicting deformation by both basal slip and kinking depending on orientation. Note that this is the second iteration of the 2019--Plummer-G-Tucker-G-J--Ti-Al-C potential, developed over both publications. This iteration is more suitable for deformation studies rather than irradiation tolerance.

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Notes: This file was provided by Gabriel Plummer on March 2, 2022 and posted with his permission.
File(s):
Citation: G. Plummer, and G.J. Tucker (2019), "Bond-order potentials for the Ti3AlC2 and Ti3SiC2 MAX phases", Physical Review B, 100(21), 214114. DOI: 10.1103/physrevb.100.214114.
Abstract: Bond-order potentials have been developed for the Ti3AlC2 and Ti3SiC2 MAX phases within the Tersoff formalism. Parameters were determined by independently considering each interatomic interaction present in the system and fitting them to the relevant structural, elastic, and defect properties for a number of unary, binary, and ternary structures. A number of material properties, including those not used in the fitting procedure, are reproduced with a high degree of accuracy when compared to experiment and ab initio calculations. Additionally, well-documented MAX phase behaviors such as plastic anisotropy and kinking nonlinear elasticity are demonstrated to be captured by the potentials. As a first highly accurate atomistic model for MAX phases, these potentials provide the opportunity to study some of the fundamental mechanisms behind unique MAX phase properties. Additionally, the fitting procedure employed is highly transferable and should be applicable to numerous other MAX phases.

Notes: This potential was designed for the study of MAX phases. In comparison to 2021--Plummer-G-Rathod-H-Srivastava-A-et-al--Ti-Al-C, this parameterization of Ti3AlC2 is more suitable for studies of irradiation tolerance rather than deformation.

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Notes: This file was taken from the supplementary material of the associated paper and posted with Gabriel Plummer's permission.
File(s):
 
Citation: S.J. Stuart, A.B. Tutein, and J.A. Harrison (2000), "A reactive potential for hydrocarbons with intermolecular interactions", The Journal of Chemical Physics, 112(14), 6472-6486. DOI: 10.1063/1.481208.
Abstract: A potential function is presented that can be used to model both chemical reactions and intermolecular interactions in condensed-phase hydrocarbon systems such as liquids, graphite, and polymers. This potential is derived from a well-known dissociable hydrocarbon force field, the reactive empirical bond-order potential. The extensions include an adaptive treatment of the nonbonded and dihedral-angle interactions, which still allows for covalent bonding interactions. Torsional potentials are introduced via a novel interaction potential that does not require a fixed hybridization state. The resulting model is intended as a first step towards a transferable, empirical potential capable of simulating chemical reactions in a variety of environments. The current implementation has been validated against structural and energetic properties of both gaseous and liquid hydrocarbons, and is expected to prove useful in simulations of hydrocarbon liquids, thin films, and other saturated hydrocarbon systems.

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Notes: Listing found at https://openkim.org.
Link(s):
 
Citation: A. Kınacı, J.B. Haskins, C. Sevik, and T. Çağın (2012), "Thermal conductivity of BN-C nanostructures", Physical Review B, 86(11), 115410. DOI: 10.1103/physrevb.86.115410.
Abstract: Chemical and structural diversity present in hexagonal boron nitride (h-BN) and graphene hybrid nanostructures provide avenues for tuning various properties for their technological applications. In this paper we investigate the variation of thermal conductivity (κ) of hybrid graphene/h-BN nanostructures: stripe superlattices and BN (graphene) dots embedded in graphene (BN) are investigated using equilibrium molecular dynamics. To simulate these systems, we have parametrized a Tersoff type interaction potential to reproduce the ab initio energetics of the B-C and N-C bonds for studying the various interfaces that emerge in these hybrid nanostructures. We demonstrate that both the details of the interface, including energetic stability and shape, as well as the spacing of the interfaces in the material, exert strong control on the thermal conductivity of these systems. For stripe superlattices, we find that zigzag configured interfaces produce a higher κ in the direction parallel to the interface than the armchair configuration, while the perpendicular conductivity is less prone to the details of the interface and is limited by the κ of h-BN. Additionally, the embedded dot structures, having mixed zigzag and armchair interfaces, affect the thermal transport properties more strongly than superlattices. The largest reduction in thermal conductivity is observed at 50% dot concentration, but the dot radius appears to have little effect on the magnitude of reduction around this concentration.

LAMMPS pair_style tersoff (2012--Kinaci-A--B-N-C--LAMMPS--ipr1)
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Notes: This file was taken from the August 22, 2018 LAMMPS distribution.
File(s):
 
Citation: A. Agrawal, and R. Mirzaeifar (2021), "Copper-Graphene Composites; Developing the MEAM Potential and Investigating their Mechanical Properties", Computational Materials Science, 188, 110204. DOI: 10.1016/j.commatsci.2020.110204.
Abstract: Unraveling the deformation mechanisms at the atomistic scale of metal matrix-graphene composites is a key step toward designing and fabricating these materials with exceptional mechanical properties. While these composites can be made by embedding graphene into multiple metallic matrices, it is shown that superior mechanical properties can be obtained by combining copper and graphene. In the past few years, molecular dynamics simulations have been used to investigate the fundamental deformation mechanisms at the nanoscale of Cu-graphene composites to facilitate designing these composites with improved mechanical properties. However, in all of the reported works, Lennard-Jones potential has been used for modeling the interaction between copper and carbon atoms. The complexities in the Cu-C interaction emerges the necessity of utilizing more accurate potentials. In this work, a 2NN MEAM (second nearest-neighbor modified embedded atomic method) potential for the copper and carbon atom interaction is developed. Since crystal structures like B1 or B2 are not experimentally available for the Cu-C system, first-principle calculations are used to determine the reference structure and its elastic constants in this work. It is shown that the B1 and B2 structure of Cu-C has positive formation energy, but B1 is dynamically stable. Accordingly, the B1 crystal structure is used as the reference structure for the Cu-C system to develop the interatomic potential. It is shown that the reported potential agrees reasonably well for phonon dispersion frequencies, stacking fault energies, and the atomic forces with the available experimental data and first-principle calculations. The developed potential is utilized to study the mechanical properties of copper-graphene composites subjected to uniaxial loading. Our results show that adding graphene to a defect-free Cu crystal weakens the metallic matrix’s mechanical properties. However, when the graphene is embedded into a Cu matrix with some defects, e.g., in a polycrystalline Cu, it can significantly improve the mechanical properties.

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Notes: These files were provided by Arpit Agrawal on August 26, 2021 and posted with his permission.
File(s):
Citation: X.W. Zhou, D.K. Ward, and M.E. Foster (2015), "An analytical bond-order potential for carbon", Journal of Computational Chemistry, 36(23), 1719-1735. DOI: 10.1002/jcc.23949.
Abstract: Carbon is the most widely studied material today because it exhibits special properties not seen in any other materials when in nano dimensions such as nanotube and graphene. Reduction of material defects created during synthesis has become critical to realize the full potential of carbon structures. Molecular dynamics (MD) simulations, in principle, allow defect formation mechanisms to be studied with high fidelity, and can, therefore, help guide experiments for defect reduction. Such MD simulations must satisfy a set of stringent requirements. First, they must employ an interatomic potential formalism that is transferable to a variety of carbon structures. Second, the potential needs to be appropriately parameterized to capture the property trends of important carbon structures, in particular, diamond, graphite, graphene, and nanotubes. Most importantly, the potential must predict the crystalline growth of the correct phases during direct MD simulations of synthesis to achieve a predictive simulation of defect formation. Because an unlimited number of structures not included in the potential parameterization are encountered, the literature carbon potentials are often not sufficient for growth simulations. We have developed an analytical bond order potential for carbon, and have made it available through the public MD simulation package LAMMPS. We demonstrate that our potential reasonably captures the property trends of important carbon phases. Stringent MD simulations convincingly show that our potential accounts not only for the crystalline growth of graphene, graphite, and carbon nanotubes but also for the transformation of graphite to diamond at high pressure.

Notes: Notes from Dr. Zhou about the C-Cu interactions: "The C-Cu potential was constructed from the carbon potential (2015--Zhou-X-W-Ward-D-K-Foster-M-E--C) and Cu of the Al-Cu and Cu-H potentials (2016--Zhou-X-W-Ward-D-K-Foster-M-E--Al-Cu, 2015--Zhou-X-W-Ward-D-K-Foster-M-Zimmerman-J-A--Cu-H), except that a Morse potential is added to the Cu so that the cohesive energy of Cu is deliberately significantly increased but the lattice constant of Cu is unchanged. This allows simulations of growth of C on Cu to be performed at temperatures higher than the Cu melting temperature (to accelerate the simulations) without other negative consequencies."

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Notes: This file was taken from the August 22, 2018 LAMMPS distribution and listed as having been created by X.W. Zhou (Sandia)
File(s):
 
Citation: L.S.I. Liyanage, S.-G. Kim, J. Houze, S. Kim, M.A. Tschopp, M.I. Baskes, and M.F. Horstemeyer (2014), "Structural, elastic, and thermal properties of cementite (Fe3C) calculated using a modified embedded atom method", Physical Review B, 89(9), 094102. DOI: 10.1103/physrevb.89.094102.
Abstract: Structural, elastic, and thermal properties of cementite (Fe3C) were studied using a modified embedded atom method (MEAM) potential for iron-carbon (Fe-C) alloys. Previously developed Fe and C single-element potentials were used to develop a Fe-C alloy MEAM potential, using a statistics-based optimization scheme to reproduce structural and elastic properties of cementite, the interstitial energies of C in bcc Fe, and heat of formation of Fe-C alloys in L12 and B1 structures. The stability of cementite was investigated by molecular dynamics simulations at high temperatures. The nine single-crystal elastic constants for cementite were obtained by computing total energies for strained cells. Polycrystalline elastic moduli for cementite were calculated from the single-crystal elastic constants of cementite. The formation energies of (001), (010), and (100) surfaces of cementite were also calculated. The melting temperature and the variation of specific heat and volume with respect to temperature were investigated by performing a two-phase (solid/liquid) molecular dynamics simulation of cementite. The predictions of the potential are in good agreement with first-principles calculations and experiments.

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Notes: These files were contributed by Laalitha Liyanage (Central Michigan Univ., Univ. of North Texas) on 14 Apr. 2014.
File(s):
Citation: K.O.E. Henriksson, C. Björkas, and K. Nordlund (2013), "Atomistic simulations of stainless steels: a many-body potential for the Fe-Cr-C system", Journal of Physics: Condensed Matter, 25(44), 445401. DOI: 10.1088/0953-8984/25/44/445401.
Abstract: Stainless steels found in real-world applications usually have some C content in the base Fe–Cr alloy, resulting in hard and dislocation-pinning carbides—Fe3C (cementite) and Cr23C6—being present in the finished steel product. The higher complexity of the steel microstructure has implications, for example, for the elastic properties and the evolution of defects such as Frenkel pairs and dislocations. This makes it necessary to re-evaluate the effects of basic radiation phenomena and not simply to rely on results obtained from purely metallic Fe–Cr alloys. In this report, an analytical interatomic potential parameterization in the Abell–Brenner–Tersoff form for the entire Fe–Cr–C system is presented to enable such calculations. The potential reproduces, for example, the lattice parameter(s), formation energies and elastic properties of the principal Fe and Cr carbides (Fe3C, Fe5C2, Fe7C3, Cr3C2, Cr7C3, Cr23C6), the Fe–Cr mixing energy curve, formation energies of simple C point defects in Fe and Cr, and the martensite lattice anisotropy, with fair to excellent agreement with empirical results. Tests of the predictive power of the potential show, for example, that Fe–Cr nanowires and bulk samples become elastically stiffer with increasing Cr and C concentrations. High-concentration nanowires also fracture at shorter relative elongations than wires made of pure Fe. Also, tests with Fe3C inclusions show that these act as obstacles for edge dislocations moving through otherwise pure Fe.

Notes: Note that this entry only represents the Fe-C subset of interatomic potentials developed and used in this reference.

LAMMPS pair_style tersoff/zbl (2013--Henriksson-K-O-E--Fe-C--LAMMPS--ipr1)
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Notes: The Tersoff/ZBL file was contributed by Astrid Gubbels-Elzas and Peter Klaver (Delft University of Technology, Netherlands) and posted with their approval and that of Krister Henriksson (Univ. of Helsinki, Finland) on 9 Jul. 2014. Note that this file only represents the Fe-C subset of interatomic potentials developed and used in this reference.
File(s):
EAM tabulated functions (2013--Henriksson-K-O-E--Fe-C--table--ipr1)
Notes: The following files were contributed by Dr. Henriksson and modified by C. Becker to include the reference and format in the header information. They represent the potential in Equation 7 of the reference, and the columns are r, VZBL, and d/dr (VZBL). They were approved by Dr. Henriksson for posting on 25 Jul. 2014.
File(s):
Citation: D.J. Hepburn, and G.J. Ackland (2008), "Metallic-covalent interatomic potential for carbon in iron", Physical Review B, 78(16), 165115. DOI: 10.1103/physrevb.78.165115.
Abstract: Existing interatomic potentials for the iron-carbon system suffer from qualitative flaws in describing even the simplest of defects. In contrast to more accurate first-principles calculations, all previous potentials show strong bonding of carbon to overcoordinated defects (e.g., self-interstitials, dislocation cores) and a failure to accurately reproduce the energetics of carbon-vacancy complexes. Thus any results from their application in molecular dynamics to more complex environments are unreliable. The problem arises from a fundamental error in potential design—the failure to describe short-ranged covalent bonding of the carbon p electrons. We describe a resolution to the problem and present an empirical potential based on insights from density-functional theory, showing covalent-type bonding for carbon. The potential correctly describes the interaction of carbon and iron across a wide range of defect environments. It has the embedded atom method form and hence appropriate for billion atom molecular-dynamics simulations.

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Notes: This file was implemented in the LAMMPS-compatible EAM/FS format by Sebastien Garruchet and posted with the permission of G.J. Ackland on 13 May 2009.
File(s):
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Notes: Listing found at https://openkim.org. This KIM potential is based on the files from 2008--Hepburn-D-J--Fe-C--LAMMPS--ipr1.
Link(s):
Citation: B.-J. Lee (2006), "A modified embedded-atom method interatomic potential for the Fe–C system", Acta Materialia, 54(3), 701-711. DOI: 10.1016/j.actamat.2005.09.034.
Abstract: A modified embedded-atom method (MEAM) interatomic potential for the Fe–C binary system has been developed using previous MEAM potentials of Fe and C. The potential parameters were determined by fitting to experimental information on the dilute heat of solution of carbon, the vacancy–carbon binding energy and its configuration, the location of interstitial carbon atoms and the migration energy of carbon atoms in body-centered cubic (bcc) Fe, and to a first-principles calculation result for the cohesive energy of a hypothetical NaCl-type FeC. The potential reproduces the known physical properties of carbon as an interstitial solute element in bcc Fe and face-centered cubic Fe very well. The applicability of this potential to atomistic approaches for investigating interactions between carbon interstitial solute atoms and other defects such as vacancies, dislocations and grain boundaries, and also for investigating the effects of carbon on various deformation and mechanical behaviors of iron is demonstrated.

LAMMPS pair_style meam (2006--Lee-B-J--Fe-C--LAMMPS--ipr1)
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Notes: These potential files were obtained from http://cmse.postech.ac.kr/home_2nnmeam, accessed Nov 9, 2020.
File(s):
See Computed Properties
Notes: Listing found at https://openkim.org.
Link(s):
 
Citation: I. Aslam, M.I. Baskes, D.E. Dickel, S. Adibi, B. Li, H. Rhee, M. Asle Zaeem, and M.F. Horstemeyer (2019), "Thermodynamic and kinetic behavior of low-alloy steels: An atomic level study using an Fe-Mn-Si-C modified embedded atom method (MEAM) potential", Materialia, 8, 100473. DOI: 10.1016/j.mtla.2019.100473.
Abstract: A quaternary element Modified Embedded Atom Method (MEAM) potential comprising Fe, Mn, Si, and C is developed by employing a hierarchical multiscale modeling paradigm to simulate low-alloy steels. Experimental information alongside first-principles calculations based on Density Functional Theory served as calibration data to upscale and develop the MEAM potential. For calibrating the single element potentials, the cohesive energy, lattice parameters, elastic constants, and vacancy and interstitial formation energies are used as target data. The heat of formation and elastic constants of binary compounds along with substitutional and interstitial formation energies serve as binary potential calibration data, while substitutional and interstitial pair binding energies aid in developing the ternary potential. Molecular dynamics simulations employing the developed potentials predict the thermal expansion coefficient, heat capacity, self-diffusion coefficients, and stacking fault energy for steel alloys comparable to those reported in the literature.

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Notes: This file was provided by Imran Aslam (Mississippi State) on Feb 28, 2020 and posted with his permission.
File(s):
 
Citation: H.-K. Kim, W.-S. Jung, and B.-J. Lee (2010), "Modified embedded-atom method interatomic potentials for the Nb-C, Nb-N, Fe-Nb-C, and Fe-Nb-N systems", Journal of Materials Research, 25(7), 1288-1297. DOI: 10.1557/jmr.2010.0182.
Abstract: Modified embedded-atom method (MEAM) interatomic potentials for Nb-C, Nb-N, Fe-Nb-C, and Fe-Nb-N systems have been developed based on the previously developed MEAM potentials for lower order systems. The potentials reproduce various fundamental physical properties (structural properties, elastic properties, thermal properties, and surface properties) of NbC and NbN, and interfacial energy between bcc Fe and NbC or NbN, in generally good agreement with higher-level calculations or experimental information. The applicability of the present potentials to atomic-level investigations to the precipitation behavior of complex-carbonitrides (Nb,Ti)(C,N) as well as NbC and NbN, and their effects on the mechanical properties of steels are also discussed.

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Notes: These potential files were obtained from http://cmse.postech.ac.kr/home_2nnmeam, accessed Nov 9, 2020.
File(s):
See Computed Properties
Notes: Listing found at https://openkim.org.
Link(s):
 
Citation: H.-K. Kim, W.-S. Jung, and B.-J. Lee (2009), "Modified embedded-atom method interatomic potentials for the Fe-Ti-C and Fe-Ti-N ternary systems", Acta Materialia, 57(11), 3140-3147. DOI: 10.1016/j.actamat.2009.03.019.
Abstract: Modified embedded-atom method (MEAM) interatomic potentials for the Fe-Ti-C and Fe-Ti-N ternary systems have been developed based on the previously developed MEAM potentials for sub-unary and binary systems. An attempt was made to find a way to determine ternary potential parameters using the corresponding binary parameters. The calculated coherent interface properties, interfacial energy, work of separation and misfit strain energy between body-centered cubic Fe and NaCl-type TiC or TiN were reasonable when compared with relevant first-principles calculations under the same condition. The applicability of the present potentials for atomistic simulations to investigate nucleation kinetics of TiC or TiN precipitates and their effects on mechanical properties in steels is also demonstrated.

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Notes: This file was submitted by Sebastián ECHEVERRI RESTREPO (SKF Engineering & Research Centre) on 31 August 2015 and approved for distribution by Byeong-Joo Lee (POSTECH). This version is compatible with LAMMPS. Implementation information can be found in FeTiC_Implementation.pdf.
File(s):
See Computed Properties
Notes: Listing found at https://openkim.org.
Link(s):
 
Citation: Z.G. Fthenakis, I.D. Petsalakis, V. Tozzini, and N.N. Lathiotakis (2022), "Evaluating the performance of ReaxFF potentials for sp2 carbon systems (graphene, carbon nanotubes, fullerenes) and a new ReaxFF potential", Frontiers in Chemistry, 10, 951261. DOI: 10.3389/fchem.2022.951261.
Abstract: 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.

Notes: The potential belongs to the type of Reax potentials, which is designed to describe interactions between condensed carbon phases (like graphene, diamond etc) and molecules composed of C, H, O and/or N atoms. It is a hybrid potential combining two other Reax potentials, namely the C-2013 potential (Srinivasan, S. G., van Duin, A. C. T., and Ganesh, P., J. Phys. Chem. A 119, 571–580 (2015)) for carbon condensed phases and RDX potential (Strachan, A., van Duin, A. C. T., Chakraborty, D., Dasgupta, S., and Goddard, W. A., Phys. Rev. Lett. 91, 098301 (2003)) for interactions between C/H/O/N atoms and molecules composed of C/H/O/N atoms, originally designed to describe initial chemical events in nitramine RDX explosions. The potential considers a hypothetical new species denoted as Cg, representing the carbon atoms in condensed carbon phases, and C, representing the carbon atoms in all other cases. The interactions between C/H/O/N atoms are described by the RDX potential, while the interactions between Cg-Cg atoms are described by a slightly modified C-2013 potential. Moreover, the interactions between Cg-C, Cg-H, Cg-O and Cg-N are also described by RDX potential, as if Cg was a C atom. The modification of GR-RDX-2021 potential with respect to the C-2013 for the Cg-Cg interactions has to do with the 39 general parameters of the potential, which has been chosen to be the parameters of the RDX potential.

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Notes: These files were provided by Zacharias Fthenakis on Nov 3, 2022. "in.graphene" and "data.graphene_H_C_O_N" provide an example LAMMPS script and corresponding atomic configuration.
File(s):
 
Citation: K. Chenoweth, A.C.T. van Duin, and W.A. Goddard (2008), "ReaxFF Reactive Force Field for Molecular Dynamics Simulations of Hydrocarbon Oxidation", The Journal of Physical Chemistry A, 112(5), 1040-1053. DOI: 10.1021/jp709896w.
Abstract: To investigate the initial chemical events associated with high-temperature gas-phase oxidation of hydrocarbons, we have expanded the ReaxFF reactive force field training set to include additional transition states and chemical reactivity of systems relevant to these reactions and optimized the force field parameters against a quantum mechanics (QM)-based training set. To validate the ReaxFF potential obtained after parameter optimization, we performed a range of NVT−MD simulations on various hydrocarbon/O2 systems. From simulations on methane/O2, o-xylene/O2, propene/O2, and benzene/O2 mixtures, we found that ReaxFF obtains the correct reactivity trend (propene > o-xylene > methane > benzene), following the trend in the C−H bond strength in these hydrocarbons. We also tracked in detail the reactions during a complete oxidation of isolated methane, propene, and o-xylene to a CO/CO2/H2O mixture and found that the pathways predicted by ReaxFF are in agreement with chemical intuition and our QM results. We observed that the predominant initiation reaction for oxidation of methane, propene, and o-xylene under fuel lean conditions involved hydrogen abstraction of the methyl hydrogen by molecular oxygen forming hydroperoxyl and hydrocarbon radical species. While under fuel rich conditions with a mixture of these hydrocarbons, we observed different chemistry compared with the oxidation of isolated hydrocarbons including a change in the type of initiation reactions, which involved both decomposition of the hydrocarbon or attack by other radicals in the system. Since ReaxFF is capable of simulating complicated reaction pathways without any preconditioning, we believe that atomistic modeling with ReaxFF provides a useful method for determining the initial events of oxidation of hydrocarbons under extreme conditions and can enhance existing combustion models.

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Notes: The file "ffield.reax.CHO_2008" was provided by Adri van Duin. From Prof. van Duin: "The ffield-file contains the force field parameters; this file is readable by LAMMPS." The ReaxFF manual (including file formatting information) was obtained from http://www.wag.caltech.edu/home/duin/manual.html. All files were posted with Prof. van Duin's approval. The standalone ReaxFF program is available without charge for academic users by emailing him.
File(s):
 
Citation: H.-K. Kim, W.-S. Jung, and B.-J. Lee (2010), "Modified embedded-atom method interatomic potentials for the Nb-C, Nb-N, Fe-Nb-C, and Fe-Nb-N systems", Journal of Materials Research, 25(7), 1288-1297. DOI: 10.1557/jmr.2010.0182.
Abstract: Modified embedded-atom method (MEAM) interatomic potentials for Nb-C, Nb-N, Fe-Nb-C, and Fe-Nb-N systems have been developed based on the previously developed MEAM potentials for lower order systems. The potentials reproduce various fundamental physical properties (structural properties, elastic properties, thermal properties, and surface properties) of NbC and NbN, and interfacial energy between bcc Fe and NbC or NbN, in generally good agreement with higher-level calculations or experimental information. The applicability of the present potentials to atomic-level investigations to the precipitation behavior of complex-carbonitrides (Nb,Ti)(C,N) as well as NbC and NbN, and their effects on the mechanical properties of steels are also discussed.

LAMMPS pair_style meam (2010--Kim-H-K--Nb-C--LAMMPS--ipr1)
See Computed Properties
Notes: These files are based on files obtained from http://cmse.postech.ac.kr/home_2nnmeam.
File(s):
See Computed Properties
Notes: Listing found at https://openkim.org.
Link(s):
 
Citation: G.-U. Jeong, and B.-J. Lee (2020), "Interatomic potentials for Pt-C and Pd-C systems and a study of structure-adsorption relationship in large Pt/graphene system", Computational Materials Science, 185, 109946. DOI: 10.1016/j.commatsci.2020.109946.
Abstract: Graphene-supported platinum (Pt) and palladium (Pd) nanoclusters have attracted attention as electrocatalysts for proton exchange membrane fuel cell (PEMFC) because of their high activity and resistance to CO poisoning. However, metal nanoparticles are weakly adsorbed to the graphene and easily migrate on the surface, causing sintering and loss of chemical activity. A thorough understanding of structure-adsorption relationship is important to design robust catalysts with high adsorption ability to stabilize metal nanoparticles, but this relationship is still not well understood, particularly in large scale systems (2–5 nm). Therefore, to investigate the structural evolution at atomic scale with atomistic simulations, we have developed interatomic potentials for the Pt-C and Pd-C binary systems, based on the second nearest-neighbor modified embedded-atom method (2NN MEAM) formalism. These potentials reproduce various fundamental properties of the alloy systems in reasonable agreement with the experimental data and first-principles calculations. Molecular dynamics simulations employing the 2NN MEAM potential were carried out to analyse structural factors that have decisive effect on the adsorption energy, by changing the symmetry of the nanoparticles and the configuration of the nanoparticles adsorbed to graphene. These factors were characterized via coordination numbers, number of Pt atoms in contact with the graphene and adsorption site. The results of our study suggest avenues for stabilizing and immobilizing metal clusters on graphene in large systems.

See Computed Properties
Notes: These potential files were obtained from http://cmse.postech.ac.kr/home_2nnmeam, accessed Nov 9, 2020.
File(s):
 
Citation: G.-U. Jeong, and B.-J. Lee (2020), "Interatomic potentials for Pt-C and Pd-C systems and a study of structure-adsorption relationship in large Pt/graphene system", Computational Materials Science, 185, 109946. DOI: 10.1016/j.commatsci.2020.109946.
Abstract: Graphene-supported platinum (Pt) and palladium (Pd) nanoclusters have attracted attention as electrocatalysts for proton exchange membrane fuel cell (PEMFC) because of their high activity and resistance to CO poisoning. However, metal nanoparticles are weakly adsorbed to the graphene and easily migrate on the surface, causing sintering and loss of chemical activity. A thorough understanding of structure-adsorption relationship is important to design robust catalysts with high adsorption ability to stabilize metal nanoparticles, but this relationship is still not well understood, particularly in large scale systems (2–5 nm). Therefore, to investigate the structural evolution at atomic scale with atomistic simulations, we have developed interatomic potentials for the Pt-C and Pd-C binary systems, based on the second nearest-neighbor modified embedded-atom method (2NN MEAM) formalism. These potentials reproduce various fundamental properties of the alloy systems in reasonable agreement with the experimental data and first-principles calculations. Molecular dynamics simulations employing the 2NN MEAM potential were carried out to analyse structural factors that have decisive effect on the adsorption energy, by changing the symmetry of the nanoparticles and the configuration of the nanoparticles adsorbed to graphene. These factors were characterized via coordination numbers, number of Pt atoms in contact with the graphene and adsorption site. The results of our study suggest avenues for stabilizing and immobilizing metal clusters on graphene in large systems.

See Computed Properties
Notes: These potential files were obtained from http://cmse.postech.ac.kr/home_2nnmeam, accessed Nov 9, 2020.
File(s):
Citation: K. Albe, K. Nordlund, and R.S. Averback (2002), "Modeling the metal-semiconductor interaction: Analytical bond-order potential for platinum-carbon", Physical Review B, 65(19), 195124. DOI: 10.1103/physrevb.65.195124.
Abstract: We propose an analytical interatomic potential for modeling platinum, carbon, and the platinum-carbon interaction using a single functional form. The ansatz chosen for this potential makes use of the fact that chemical bonding in both covalent systems and d-transition metals can be described in terms of the Pauling bond order. By adopting Brenner’s original bond-order potential for carbon [Phys. Rev. B 42, 9458 (1990)] we devise an analytical expression that has an equivalent form for describing the C-C/Pt-Pt/Pt-C interactions. It resembles, in the case of the pure metal interaction, an embedded-atom scheme, but includes angularity. The potential consequently provides an excellent description of the properties of Pt including the elastic anisotropy ratio. The parameters for both the Pt-Pt interaction and the Pt-C interaction are systematically adjusted using a combination of experimental and theoretical data, the latter being generated by total-energy calculations based on density-functional theory. This approach offers good chemical accuracy in describing all types of interactions, and has a wide applicability for modeling metal-semiconductor systems.

 
Citation: K.-H. Kang, T. Eun, M.-C. Jun, and B.-J. Lee (2014), "Governing factors for the formation of 4H or 6H-SiC polytype during SiC crystal growth: An atomistic computational approach", Journal of Crystal Growth, 389, 120-133. DOI: 10.1016/j.jcrysgro.2013.12.007.
Abstract: The effects of various process variables on the formation of polytypes during SiC single crystal growths have been investigated using atomistic simulations based on an empirical potential (the second nearest-neighbor MEAM) and first-principles calculation. It is found out that the main role of process variables (temperature, surface type, growth rate, atmospheric condition, dopant type, etc.) is not to directly change the relative stability of SiC polytypes directly but to change the formation tendency of point defects. The biaxial local strain due to the formation of point defects is found to have an effect on the relative stability of SiC polytypes and is proposed in the present study as a governing factor that affects the selective growth of SiC polytypes. Based on the present local strain scheme, the competitive growth among SiC polytypes, especially the 4H and 6H-SiC, available in literatures can be reasonably explained by interpreting the effect of each process variable in terms of defect formation and the resultant local strain. Those results provide an insight into the selective growth of SiC polytypes and also help us obtain high quality SiC single crystals.

See Computed Properties
Notes: These potential files were obtained from http://cmse.postech.ac.kr/home_2nnmeam, accessed Nov 9, 2020.
File(s):
See Computed Properties
Notes: Listing found at https://openkim.org.
Link(s):
Citation: C. Jiang, D. Morgan, and I. Szlufarska (2012), "Carbon tri-interstitial defect: A model for the DII center", Physical Review B, 86(14), 144118. DOI: 10.1103/physrevb.86.144118.
Abstract: Using a combination of random configuration sampling, molecular dynamics simulated annealing with empirical potential, and ensuing structural refinement by first-principles density functional calculations, we perform an extensive ground-state search for the most stable configurations of small carbon interstitial clusters in SiC. Our search reveals a "magic" cluster number of three atoms, where the formation energy per interstitial shows a distinct minimum. A carbon tri-interstitial cluster with trigonal C3v symmetry is discovered, in which all carbon atoms are fourfold coordinated. In addition to its special thermodynamic stability, its localized vibrational modes are also in a very good agreement with the experimental photoluminescence spectra of the DII center in both 3C- and 4H-SiC. The DII center is one of the most persistent defects in SiC, and we propose that the discovered carbon tri-interstitial is responsible for this center.

LAMMPS pair_style edip/multi (2012--Jiang-C--Si-C--LAMMPS--ipr1)
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Notes: This file was taken from the August 22, 2018 LAMMPS distribution. It is listed as being contributed by Chao Jiang (University of Wisconsin)
File(s):
Citation: P. Vashishta, R.K. Kalia, A. Nakano, and J.P. Rino (2007), "Interaction potential for silicon carbide: A molecular dynamics study of elastic constants and vibrational density of states for crystalline and amorphous silicon carbide", Journal of Applied Physics, 101(10), 103515. DOI: 10.1063/1.2724570.
Abstract: An effective interatomic interaction potential for SiC is proposed. The potential consists of two-body and three-body covalent interactions. The two-body potential includes steric repulsions due to atomic sizes, Coulomb interactions resulting from charge transfer between atoms, charge-induced dipole-interactions due to the electronic polarizability of ions, and induced dipole-dipole (van der Waals) interactions. The covalent characters of the Si–C–Si and C–Si–C bonds are described by the three-body potential. The proposed three-body interaction potential is a modification of the Stillinger-Weber form proposed to describe Si. Using the molecular dynamics method, the interaction potential is used to study structural, elastic, and dynamical properties of crystalline (3C), amorphous, and liquid states of SiC for several densities and temperatures. The structural energy for cubic (3C) structure has the lowest energy, followed by the wurtzite (2H) and rock-salt (RS) structures. The pressure for the structural transformation from 3C-to-RS from the common tangent is found to be 90 GPa. For 3C-SiC, our computed elastic constants (C11, C12, and C44), melting temperature, vibrational density-of-states, and specific heat agree well with the experiments. Predictions are made for the elastic constant as a function of density for the crystalline and amorphous phase. Structural correlations, such as pair distribution function and neutron and x-ray static structure factors are calculated for the amorphous and liquid state.

LAMMPS pair_style vashishta (2007--Vashishta-P--Si-C--LAMMPS--ipr1)
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Notes: This file was taken from the August 22, 2018 LAMMPS distribution.
File(s):
Citation: P. Erhart, and K. Albe (2005), "Analytical potential for atomistic simulations of silicon, carbon, and silicon carbide", Physical Review B, 71(3), 035211. DOI: 10.1103/physrevb.71.035211.
Abstract: We present an analytical bond-order potential for silicon, carbon, and silicon carbide that has been optimized by a systematic fitting scheme. The functional form is adopted from a preceding work [Phys. Rev. B 65, 195124 (2002)] and is built on three independently fitted potentials for Si-Si, C-C, and Si-C interaction. For elemental silicon and carbon, the potential perfectly reproduces elastic properties and agrees very well with first-principles results for high-pressure phases. The formation enthalpies of point defects are reasonably reproduced. In the case of silicon stuctural features of the melt agree nicely with data taken from literature. For silicon carbide the dimer as well as the solid phases B1, B2, and B3 were considered. Again, elastic properties are very well reproduced including internal relaxations under shear. Comparison with first-principles data on point defect formation enthalpies shows fair agreement. The successful validation of the potentials for configurations ranging from the molecular to the bulk regime indicates the transferability of the potential model and makes it a good choice for atomistic simulations that sample a large configuration space.

Notes: This entry uses the paper's Si-I interaction, which was recommended for SiC simulations.

LAMMPS pair_style tersoff (2005--Erhart-P--Si-C-I--LAMMPS--ipr1)
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Notes: This file was created and verified by Lucas Hale. The parameter values are comparable to those in the SiC_Erhart-Albe.tersoff file in the August 22, 2018 LAMMPS distribution with this file using higher precision for the derived parameters.
File(s):
See Computed Properties
Notes: Listing found at https://openkim.org. This KIM potential is based on the SiC_Erhart-Albe.tersoff file from the LAMMPS potentials directory.
Link(s):
Citation: P. Erhart, and K. Albe (2005), "Analytical potential for atomistic simulations of silicon, carbon, and silicon carbide", Physical Review B, 71(3), 035211. DOI: 10.1103/physrevb.71.035211.
Abstract: We present an analytical bond-order potential for silicon, carbon, and silicon carbide that has been optimized by a systematic fitting scheme. The functional form is adopted from a preceding work [Phys. Rev. B 65, 195124 (2002)] and is built on three independently fitted potentials for Si-Si, C-C, and Si-C interaction. For elemental silicon and carbon, the potential perfectly reproduces elastic properties and agrees very well with first-principles results for high-pressure phases. The formation enthalpies of point defects are reasonably reproduced. In the case of silicon stuctural features of the melt agree nicely with data taken from literature. For silicon carbide the dimer as well as the solid phases B1, B2, and B3 were considered. Again, elastic properties are very well reproduced including internal relaxations under shear. Comparison with first-principles data on point defect formation enthalpies shows fair agreement. The successful validation of the potentials for configurations ranging from the molecular to the bulk regime indicates the transferability of the potential model and makes it a good choice for atomistic simulations that sample a large configuration space.

Notes: This entry uses the paper's Si-II interaction, which gives better elastic and thermal properties for elemental silicon.

LAMMPS pair_style tersoff (2005--Erhart-P--Si-C-II--LAMMPS--ipr1)
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Notes: This file was created and verified by Lucas Hale. The parameter values are identical to the ones in the parameter file used by openKIM model MO_408791041969_001.
File(s):
See Computed Properties
Notes: Listing found at https://openkim.org. This KIM potential is based on a parameter file with identical parameter values as 2005--Erhart-P--Si-C-II--LAMMPS--ipr1.
Link(s):
Citation: R. Devanathan, T. Diaz de la Rubia, and W.J. Weber (1998), "Displacement threshold energies in β-SiC", Journal of Nuclear Materials, 253(1-3), 47-52. DOI: 10.1016/s0022-3115(97)00304-8.
Abstract: We have calculated the displacement threshold energies (Ed) for C and Si primary knock-on atoms (PKA) in β-SiC using molecular dynamic simulations. The interactions between atoms were modeled using a modified form of the Tersoff potential in combination with a realistic repulsive potential obtained from density-functional theory calculations. The simulation cell was cubic, contained 8000 atoms and had periodic boundaries. The temperature of the simulation was about 150 K. Our results indicate strong anisotropy in the Ed values for both Si and C PKA. The displacement threshold for Si varies from about 36 eV along [001] to 113 eV along [111], while Ed for C varies from 28 eV along [111] to 71 eV along [111]. These results are in good agreement with experimental observations.

LAMMPS pair_style tersoff/zbl (1998--Devanathan-R--Si-C--LAMMPS--ipr1)
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Notes: This file was taken from the August 22, 2018 LAMMPS distribution.
File(s):
Citation: J. Tersoff (1994), "Chemical order in amorphous silicon carbide", Physical Review B, 49(23), 16349-16352. DOI: 10.1103/physrevb.49.16349.
Abstract: While ordering in alloy crystals is well understood, short-range ordering in amorphous alloys remains controversial. Here, by studying computer-generated models of amorphous SiC, we show that there are two principal factors controlling the degree of chemical order in amorphous covalent alloys. One, the chemical preference for mixed bonds, is much the same in crystalline and amorphous materials. However, the other factor, the atomic size difference, is far less effective at driving ordering in amorphous material than in the crystal. As a result, the amorphous phase may show either strong ordering (as in GaAs), or weaker ordering (as in SiC), depending upon the relative importance of these two factors.

Notes: This parameterization uses the interactions of 1990--Tersoff-J--Si-C and the cutoff of 1989--Tersoff-J--Si-C, with a slight correction for heat of mixing.

LAMMPS pair_style tersoff (1994--Tersoff-J--Si-C--LAMMPS--ipr1)
See Computed Properties
Notes: This file was created and verified by Lucas Hale. The parameter values are comparable to the SiC_1994.tersoff file in the August 22, 2018 LAMMPS distribution, with this file having higher numerical precision for the derived mixing parameters.
File(s):
Citation: J. Tersoff (1990), "Carbon defects and defect reactions in silicon", Physical Review Letters, 64(15), 1757-1760. DOI: 10.1103/physrevlett.64.1757.
Abstract: The energies of carbon defects in silicon are calculated, using an empirical classical potential, and used to infer defect properties and reactions. Substitutional carbon is found to react with silicon interstitials, with the carbon "kicked out" to form a (100) split interstitial. This interstitial can in turn bind to a second substitutional carbon, relieving stress, in three configurations with similar energies. The results here accord well with a variety of experimental data, including defect structures, activation energies for defect motion, and coupling to strain. A discrepancy with the accepted values for carbon solubility in silicon suggests a reinterpretation of the experimental data.

Notes: This parameterization focused on studying C interstitials in bulk Si. It has a sharp cutoff not suited for unconstrained simulations.

LAMMPS pair_style tersoff (1990--Tersoff-J--Si-C--LAMMPS--ipr1)
See Computed Properties
Notes: This file was created and verified by Lucas Hale. The parameter values are comparable to the SiC_1990.tersoff file in the August 22, 2018 LAMMPS distribution, with this file having higher numerical precision for the derived mixing parameters.
File(s):
Citation: J. Tersoff (1989), "Modeling solid-state chemistry: Interatomic potentials for multicomponent systems", Physical Review B, 39(8), 5566-5568. DOI: 10.1103/physrevb.39.5566.
Abstract: A general form is proposed for an empirical interatomic potential for multicomponent systems. This form interpolates between potentials for the respective elements to treat heteronuclear bonds. The approach is applied to C-Si and Si-Ge systems. In particular, the properties of SiC and its defects are well described.
Citation: J. Tersoff (1990), "Erratum: Modeling solid-state chemistry: Interatomic potentials for multicomponent systems", Physical Review B, 41(5), 3248-3248. DOI: 10.1103/physrevb.41.3248.2.

Notes: This is Tersoff's original multicomponent potential for Si-C interactions.

LAMMPS pair_style tersoff (1989--Tersoff-J--Si-C--LAMMPS--ipr1)
See Computed Properties
Notes: This file was created and verified by Lucas Hale. The parameter values are comparable to the Si(D)-C interactions in SiCGe.tersoff file in the August 22, 2018 LAMMPS distribution, with this file having higher numerical precision for the derived mixing parameters.
File(s):
See Computed Properties
Notes: Listing found at https://openkim.org. This KIM potential is based on a parameter file with identical parameter values as 1989--Tersoff-J--Si-C--LAMMPS--ipr1.
Link(s):
 
Citation: G. Plummer, and G.J. Tucker (2019), "Bond-order potentials for the Ti3AlC2 and Ti3SiC2 MAX phases", Physical Review B, 100(21), 214114. DOI: 10.1103/physrevb.100.214114.
Abstract: Bond-order potentials have been developed for the Ti3AlC2 and Ti3SiC2 MAX phases within the Tersoff formalism. Parameters were determined by independently considering each interatomic interaction present in the system and fitting them to the relevant structural, elastic, and defect properties for a number of unary, binary, and ternary structures. A number of material properties, including those not used in the fitting procedure, are reproduced with a high degree of accuracy when compared to experiment and ab initio calculations. Additionally, well-documented MAX phase behaviors such as plastic anisotropy and kinking nonlinear elasticity are demonstrated to be captured by the potentials. As a first highly accurate atomistic model for MAX phases, these potentials provide the opportunity to study some of the fundamental mechanisms behind unique MAX phase properties. Additionally, the fitting procedure employed is highly transferable and should be applicable to numerous other MAX phases.

Notes: This potential was designed for the study of MAX phases.

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Notes: This file was taken from the supplementary material of the associated paper and posted with Gabriel Plummer's permission.
File(s):
 
Citation: Y.-M. Kim, and B.-J. Lee (2008), "Modified embedded-atom method interatomic potentials for the Ti-C and Ti-N binary systems", Acta Materialia, 56(14), 3481-3489. DOI: 10.1016/j.actamat.2008.03.027.
Abstract: Modified embedded-atom method (MEAM) interatomic potentials for the Ti-C and Ti-N binary systems have been developed using previously developed MEAM potentials of Ti, C and N. The potential parameters were determined by fitting to experimental data on the enthalpy of formation, lattice parameter, elastic constants, thermal linear expansion of NaCl-type TiC and TiN, and dilute heat of solution of carbon and nitrogen atoms in hexagonal close-packed Ti. The potentials can describe fundamental physical properties (structural, elastic, thermal and surface properties) of the alloys well, in good agreement with experimental information or first-principles calculations. The applicability of the potentials to atomistic investigations of interactions between TiC or TiN precipitates and matrix, dislocations or other defects, and their effects on deformation and mechanical behaviors of metallic alloys is discussed.

LAMMPS pair_style meam (2008--Kim-Y-M--Ti-C--LAMMPS--ipr1)
See Computed Properties
Notes: These potential files were obtained from http://cmse.postech.ac.kr/home_2nnmeam, accessed Nov 9, 2020.
File(s):
See Computed Properties
Notes: Listing found at https://openkim.org.
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Citation: S. Nouranian, M.A. Tschopp, S.R. Gwaltney, M.I. Baskes, and M.F. Horstemeyer (2014), "An interatomic potential for saturated hydrocarbons based on the modified embedded-atom method", Physical Chemistry Chemical Physics, 16(13), 6233-6249. DOI: 10.1039/c4cp00027g.
Abstract: In this work, we developed an interatomic potential for saturated hydrocarbons using the modified embedded-atom method (MEAM), a reactive semi-empirical many-body potential based on density functional theory and pair potentials. We parameterized the potential by fitting to a large experimental and first-principles (FP) database consisting of (1) bond distances, bond angles, and atomization energies at 0 K of a homologous series of alkanes and their select isomers from methane to n-octane, (2) the potential energy curves of H2, CH, and C2 diatomics, (3) the potential energy curves of hydrogen, methane, ethane, and propane dimers, i.e., (H2)2, (CH4)2, (C2H6)2, and (C3H8)2, respectively, and (4) pressure–volume–temperature (PVT) data of a dense high-pressure methane system with the density of 0.5534 g cc−1. We compared the atomization energies and geometries of a range of linear alkanes, cycloalkanes, and free radicals calculated from the MEAM potential to those calculated by other commonly used reactive potentials for hydrocarbons, i.e., second-generation reactive empirical bond order (REBO) and reactive force field (ReaxFF). MEAM reproduced the experimental and/or FP data with accuracy comparable to or better than REBO or ReaxFF. The experimental PVT data for a relatively large series of methane, ethane, propane, and butane systems with different densities were predicted reasonably well by the MEAM potential. Although the MEAM formalism has been applied to atomic systems with predominantly metallic bonding in the past, the current work demonstrates the promising extension of the MEAM potential to covalently bonded molecular systems, specifically saturated hydrocarbons and saturated hydrocarbon-based polymers. The MEAM potential has already been parameterized for a large number of metallic unary, binary, ternary, carbide, nitride, and hydride systems, and extending it to saturated hydrocarbons provides a reliable and transferable potential for atomistic/molecular studies of complex material phenomena involving hydrocarbon–metal or polymer–metal interfaces, polymer–metal nanocomposites, fracture and failure in hydrocarbon-based polymers, etc. The latter is especially true since MEAM is a reactive potential that allows for dynamic bond formation and bond breaking during simulation. Our results show that MEAM predicts the energetics of two major chemical reactions for saturated hydrocarbons, i.e., breaking a C–C and a C–H bond, reasonably well. However, the current parameterization does not accurately reproduce the energetics and structures of unsaturated hydrocarbons and, therefore, should not be applied to such systems.

Notes: Dr. Sasan Nouranian (Center for Advanced Vehicular Systems, Mississippi State Univ.) noted: "These MEAM parameters for elements C and H as well as the diatomic CH are appropriate for energy minimization and reactive molecular dynamics simulations of SATURATED hydrocarbons, where all carbon atoms have the sp3 hybridization (single C-C bonds). At the current state, MEAM cannot handle unsaturated compounds with great accuracy. Furthermore, these C and H parameters are not appropriate for diamond and graphite systems. For the first time, MEAM can be used to simulate hydrocarbons and hydrocarbon/metal systems, since it has a large parameter database for major metals in the periodic table of elements. Since MEAM is a reactive potential, it can also be used to simulate fracture and fatigue in hydrocarbon-based polymers, such as polyethylene and polypropylene and their composites with nanometals as well as polymer/metal interfaces."

LAMMPS pair_style meam (2014--Nouranian-S--CH--ipr1)
Notes: These files were contributed by Sasan Nouranian (Center for Advanced Vehicular Systems, Mississippi State Univ.) on 1 Jul. 2014. An example of energy minimization for an isobutane molecule using the MEAM potential in LAMMPS is also included (Isobutane.in and Isobutane.dat).
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Date Created: October 5, 2010 | Last updated: November 18, 2022