× Updated! Potentials that share interactions are now listed as related models.
 
Citation: R.S. Elliott, and A. Akerson (2015), "Efficient "universal" shifted Lennard-Jones model for all KIM API supported species".

Notes: This is the O 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.

See Computed Properties
Notes: Listing found at https://openkim.org.
Link(s):
 
Citation: H. Gao, A. Otero-de-la-Roza, S.M. Aouadi, E.R. Johnson, and A. Martini (2013), "An empirical model for silver tantalate", Modelling and Simulation in Materials Science and Engineering, 21(5), 055002. DOI: 10.1088/0965-0393/21/5/055002.
Abstract: A set of parameters for the modified embedded atom method (MEAM) potential was developed to describe the perovskite silver tantalate (AgTaO3). First, MEAM parameters for AgO and TaO were determined based on the structural and elastic properties of the materials in a B1 reference structure predicted by density-functional theory (DFT). Then, using the fitted binary parameters, additional potential parameters were adjusted to enable the empirical potential to reproduce DFT-predicted lattice structure, elastic constants, cohesive energy and equation of state for the ternary AgTaO3. Finally, thermal expansion was predicted by a molecular dynamics (MD) simulation using the newly developed potential and compared directly to experimental values. The agreement with known experimental data for AgTaO3 is satisfactory, and confirms that the new empirical model is a good starting point for further MD studies.

LAMMPS pair_style meam (2013--Gao-H--AgTaO3--LAMMPS--ipr2)
See Computed Properties
Notes: These files were sent by Dr. Ashlie Martini (Univ. California Merced) and approved for distribution on 6 Jul. 2013. The file AgTaO3_40atoms.dat contains atomic coordinates for the 40-atom cell described in the paper. A sample LAMMPS input script to calculate the cohesive energy of that configuration is in in.AgTaO3. This potential was tested on the following versions of LAMMPS: 5Mar12, 12Apr12, 19May12, 4Jul12, 28Oct12, 21Feb13, 5Jun13, 13Jun13, 17Jun13.
File(s):
 
Citation: A. Kumar, A. Chernatynskiy, T. Liang, K. Choudhary, M.J. Noordhoek, Y.-T. Cheng, S.R. Phillpot, and S.B. Sinnott (2015), "Charge optimized many-body (COMB) potential for dynamical simulation of Ni-Al phases", Journal of Physics: Condensed Matter, 27(33), 336302. DOI: 10.1088/0953-8984/27/33/336302.
Abstract: An interatomic potential for the Ni–Al system is presented within the third-generation charge optimized many-body (COMB3) formalism. The potential has been optimized for Ni3Al, or the γ' phase in Ni-based superalloys. The formation energies predicted for other Ni–Al phases are in reasonable agreement with first-principles results. The potential further predicts good mechanical properties for Ni3Al, which includes the values of the complex stacking fault (CSF) and the anti-phase boundary (APB) energies for the (1 1 1) and (1 0 0) planes. It is also used to investigate dislocation propagation across the Ni3Al (1 1 0)–Ni (1 1 0) interface, and the results are consistent with simulation results reported in the literature. The potential is further used in combination with a recent COMB3 potential for Al2O3 to investigate the Ni3Al (1 1 1)–Al2O3 (0 0 0 1) interface, which has not been modeled previously at the classical atomistic level due to the lack of a reactive potential to describe both Ni3Al and Al2O3 as well as interactions between them. The calculated work of adhesion for this interface is predicted to be 1.85 J m−2, which is in agreement with available experimental data. The predicted interlayer distance is further consistent with the available first-principles results for Ni (1 1 1)–Al2O3 (0 0 0 1).

See Computed Properties
Notes: This file was obtained from Jarvis-FF (https://www.ctcms.nist.gov/~knc6/periodic.html) on 9 Nov. 2018 and posted at Kamal Choudhary's (NIST) request.
File(s):
 
Citation: K. Choudhary, T. Liang, A. Chernatynskiy, S.R. Phillpot, and S.B. Sinnott (2015), "Charge optimized many-body (COMB) potential for Al2O3 materials, interfaces, and nanostructures", Journal of Physics: Condensed Matter, 27(30), 305004. DOI: 10.1088/0953-8984/27/30/305004.
Abstract: This work presents the development and applications of a new empirical, variable chargepotential for Al2O3 systems within the charge optimized many-body (COMB) potential framework. The potential can describe the fundamental physical properties of Al2O3, including cohesive energy, elastic constants, defect formation energies, surface energies and phonon properties of α-Al2O3 comparable to that obtained from experiments and first-principles calculations. The potential is further employed in classical molecular dynamics (MD) simulations to validate and predict the properties of the Al (1 1 1)–Al2O3 (0 0 0 1) interface, tensile properties of Al nanowires, Al2O3 nanowires, Al2O3-covered Al nanowires, and defective Al2O3 nanowires. The results demonstrate that the potential is well-suited to model heterogeneous material systems involving Al and Al2O3. Most importantly, the parameters can be seamlessly coupled with COMB3 parameters for other materials to enable MD simulations of a wide range of heterogeneous material systems.

See Computed Properties
Notes: This file was obtained from Jarvis-FF (https://www.ctcms.nist.gov/~knc6/periodic.html) on 9 Nov. 2018 and posted at Kamal Choudhary's (NIST) request.
File(s):
 
Citation: J. Byggmästar, E.A. Hodille, Y. Ferro, and K. Nordlund (2018), "Analytical bond order potential for simulations of BeO 1D and 2D nanostructures and plasma-surface interactions", Journal of Physics: Condensed Matter, 30(13), 135001. DOI: 10.1088/1361-648x/aaafb3.
Abstract: An analytical interatomic bond order potential for the Be–O system is presented. The potential is fitted and compared to a large database of bulk BeO and point defect properties obtained using density functional theory. Its main applications include simulations of plasma-surface interactions involving oxygen or oxide layers on beryllium, as well as simulations of BeO nanotubes and nanosheets. We apply the potential in a study of oxygen irradiation of Be surfaces, and observe the early stages of an oxide layer forming on the Be surface. Predicted thermal and elastic properties of BeO nanotubes and nanosheets are simulated and compared with published ab initio data.

Notes: J. Byggmästar (University of Helsinki) noted that the pure elemental potentials for Be-Be and O-O are from the following references:
Be-Be: Björkas, C., Juslin, N., Timko, H., Vörtler, K., Nordlund, K., Henriksson, K., & Erhart, P. (2009). Interatomic potentials for the Be–C–H system. Journal of Physics: Condensed Matter, 21(44), 445002. DOI: 10.1088/0953-8984/21/44/445002
O-O: Erhart, P., Juslin, N., Goy, O., Nordlund, K., Müller, R., & Albe, K. (2006). Analytic bond-order potential for atomistic simulations of zinc oxide. Journal of Physics: Condensed Matter, 18(29), 6585–6605. DOI: https://doi.org/10.1088/0953-8984/18/29/003
which should be cited if only the Be-Be or O-O parts are used.

LAMMPS pair_style tersoff/zbl (2018--Byggmastar-J--Be-O--LAMMPS--ipr1)
See Computed Properties
Notes: These files were sent by J. Byggmästar (University of Helsinki) on 6 Mar. 2018 and posted with his permission.
File(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.

See Computed Properties
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.

See Computed Properties
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: P. Broqvist, J. Kullgren, M.J. Wolf, A.C.T. van Duin, and K. Hermansson (2015), "ReaxFF Force-Field for Ceria Bulk, Surfaces, and Nanoparticles", The Journal of Physical Chemistry C, 119(24), 13598-13609. DOI: 10.1021/acs.jpcc.5b01597.
Abstract: We have developed a reactive force-field of the ReaxFF type for stoichiometric ceria (CeO2) and partially reduced ceria (CeO2–x). We describe the parametrization procedure and provide results validating the parameters in terms of their ability to accurately describe the oxygen chemistry of the bulk, extended surfaces, surface steps, and nanoparticles of the material. By comparison with our reference electronic structure method (PBE+U), we find that the stoichiometric bulk and surface systems are well reproduced in terms of bulk modulus, lattice parameters, and surface energies. For the surfaces, step energies on the (111) surface are also well described. Upon reduction, the force-field is able to capture the bulk and surface vacancy formation energies (Evac), and in particular, it reproduces the Evac variation with depth from the (110) and (111) surfaces. The force-field is also able to capture the energy hierarchy of differently shaped stoichiometric nanoparticles (tetrahedra, octahedra, and cubes), and of partially reduced octahedra. For these reasons, we believe that this force-field provides a significant addition to the method repertoire available for simulating redox properties at ceria surfaces.

Notes: J. Kullgren included the following notes: "Usage: The parameters have been tested for static calculations of CeO2 and partially reduced CeO(2-x) using the LAMMPS code with the fortran implementation of reaxFF. For energy comparisons, use the in-cell approach (see the paper) when calculating reaction energies. Note to the users: After publication we have made further use of the published ceria parameters and noticed an additional (false) local minimum occurring for partially reduced ceria at a short Ce-O distance (approx. 1.89 Angstrom). This may (for example) have consequences for dynamic simulations at moderate temperatures. Our attempts to heal this deficiency have so far destroyed the good performance regarding the ordering of the surface vacancy energies on the (111) surface. In relevant cases, we advice our users to analyze the bond distances from the simulations."

LAMMPS pair_style reax/c (2015--Broqvist-P--Ce-O--LAMMPS--ipr1)
See Computed Properties
Notes: This file was sent by J. Kullgren (Uppsala University) on 19 December 2016 and posted with his permission. Update March 15, 2020: This version was identified to not be compatible with LAMMPS.
File(s): retracted


LAMMPS pair_style reax/c (2015--Broqvist-P--Ce-O--LAMMPS--ipr2)
See Computed Properties
Notes: These files were posted on March 15, 2020 by Lucas Hale. They modify the above version by separating the comments into a separate file, making the parameter file compatible with LAMMPS.
File(s):
 
Citation: E. Lee, K.-R. Lee, and B.-J. Lee (2018), "An interatomic potential for the Li-Co-O ternary system", Computational Materials Science, 142, 47-58. DOI: 10.1016/j.commatsci.2017.10.010.
Abstract: Although large-scale atomistic simulations provide useful insights into various material phenomena, such studies on LiCoO2, which is the most widely used cathode material for lithium ion batteries (LIBs), have rarely been undertaken due to difficulties in developing adequate interatomic potentials. In this study, an interatomic potential (2NNMEAM + Qeq) for the Li-Co-O ternary system is developed to carry out molecular dynamics (MD) simulation studies on lithium cobalt oxides. Potential parameters are optimized so that the potential can successfully reproduce fundamental materials properties (structural, elastic, thermodynamic and migration properties) of various compounds of sub-binary and lithium cobalt ternary oxide systems. Through MD simulations, we investigate lithium diffusion properties (activation energy for lithium migration and diffusion coefficient) in layered Li1−xCoO2 (0 ≤ x ≤ 0.5) of various lithium vacancy concentrations. We find that the lithium vacancy concentration has a significant influence on the activation energy for lithium diffusion and the lithium diffusion coefficient in the Li1−xCoO2 cathode. The developed potential can be further utilized for atomistic simulation studies on other materials phenomena (phase transitions, defect formation, lithiation/delithiation, etc.) in LIB cathode materials.

hybrid/overlay coul/streitz meam (2018--Lee-E--Li-Co-O--LAMMPS--ipr1)
See Computed Properties
Notes: These files were obtained from http://cmse.postech.ac.kr/home_2nnmeam, accessed Nov 9, 2020. More information on using the 2NNMEAM-QEQ potentials can be found at https://cmse.postech.ac.kr/lammps/140341.
File(s):
 
Citation: J. Byggmästar, M. Nagel, K. Albe, K. Henriksson, and K. Nordlund (2019), "Analytical interatomic bond-order potential for simulations of oxygen defects in iron", Journal of Physics: Condensed Matter, 31, 215401. DOI: 10.1088/1361-648x/ab0931.
Abstract: We present an analytical bond-order potential for the Fe–O system, capable of reproducing the basic properties of wüstite as well as the energetics of oxygen impurities in α-iron. The potential predicts binding energies of various small oxygen-vacancy clusters in α-iron in good agreement with density functional theory results, and is therefore suitable for simulations of oxygen-based defects in iron. We apply the potential in simulations of the stability and structure of Fe/FeO interfaces and FeO precipitates in iron, and observe that the shape of FeO precipitates can change due to formation of well-defined Fe/FeO interfaces. The interface with crystalline Fe also ensures that the precipitates never become fully amorphous, no matter how small they are.

Notes: The potential is not suitable for simulations of the Fe2O3 and Fe3O4 phases.

LAMMPS pair_style tersoff/zbl (2019--Byggmastar-J--Fe-O--LAMMPS--ipr1)
See Computed Properties
Notes: This file was provided by Jesper Byggmästar (University of Helsinki) on 20 March 2019 and posted with his permission.
File(s):
 
Citation: G. Sivaraman, L. Gallington, A.N. Krishnamoorthy, M. Stan, G. Csányi, Vázquez-Mayagoitia, and C.J. Benmore (2021), "Experimentally Driven Automated Machine-Learned Interatomic Potential for a Refractory Oxide", Physical Review Letters, 126(15), 156002. DOI: 10.1103/physrevlett.126.156002.
Abstract: Understanding the structure and properties of refractory oxides is critical for high temperature applications. In this work, a combined experimental and simulation approach uses an automated closed loop via an active learner, which is initialized by x-ray and neutron diffraction measurements, and sequentially improves a machine-learning model until the experimentally predetermined phase space is covered. A multiphase potential is generated for a canonical example of the archetypal refractory oxide, HfO2, by drawing a minimum number of training configurations from room temperature to the liquid state at ~2900°C. The method significantly reduces model development time and human effort.

 
Citation: E. Lee, K.-R. Lee, and B.-J. Lee (2017), "Interatomic Potential of Li–Mn–O and Molecular Dynamics Simulations on Li Diffusion in Spinel Li1–xMn2O4", The Journal of Physical Chemistry C, 121(24), 13008-13017. DOI: 10.1021/acs.jpcc.7b02727.
Abstract: An interatomic potential of the Li–Mn–O ternary system has been developed on the basis of the second-nearest-neighbor modified embedded-atom method (2NN MEAM) formalism combined with a charge equilibration (Qeq) concept. The potential reproduces fundamental physical properties (structural, elastic, thermodynamic and migration properties) of various compounds well, including lithium oxides, manganese oxides, and lithium manganese ternary oxides. Through molecular dynamics (MD) simulations using the developed potential, lithium diffusion properties (activation energy for lithium migration and diffusion coefficient) in spinel Li1–xMn2O4 are also reproduced in good agreement with experiments. We have found that the effect of the lithium vacancy concentration is marginal on the activation energy for lithium diffusion in the Li1–xMn2O4 cathode, but it is significant in the lithium diffusion coefficient. The potential can be further utilized for atomistic simulations of various materials phenomena (phase transitions, defect formation, lithiation/delithiation, etc.) in LIB cathode materials.

hybrid/overlay coul/streitz meam (2017--Lee-E--Li-Mn-O--LAMMPS--ipr1)
See Computed Properties
Notes: These files were obtained from http://cmse.postech.ac.kr/home_2nnmeam, accessed Nov 9, 2020. More information on using the 2NNMEAM-QEQ potentials can be found at https://cmse.postech.ac.kr/lammps/140341.
File(s):
 
Citation: P. Tiwary, A. Walle, B. Jeon, and N. Grønbech-Jensen (2011), "Interatomic potentials for mixed oxide and advanced nuclear fuels", Physical Review B, 83(9), 094104. DOI: 10.1103/physrevb.83.094104.
Abstract: We extend our recently developed interatomic potentials for UO2 to the fuel system (U,Pu,Np)O2. We do so by fitting against an extensive database of ab initio results as well as to experimental measurements. The applicability of these interactions to a variety of mixed environments beyond the fitting domain is also assessed. The employed formalism makes these potentials applicable across all interatomic distances without the need for any ambiguous splining to the well-established short-range Ziegler-Biersack-Littmark universal pair potential. We therefore expect these to be reliable potentials for carrying out damage simulations (and molecular dynamics simulations in general) in nuclear fuels of varying compositions for all relevant atomic collision energies.
Citation: P. Tiwary, A. van de Walle, and N. Grønbech-Jensen (2009), "Ab initio construction of interatomic potentials for uranium dioxide across all interatomic distances", Physical Review B, 80(17), 174302. DOI: 10.1103/physrevb.80.174302.
Abstract: We provide a methodology for generating interatomic potentials for use in classical molecular-dynamics simulations of atomistic phenomena occurring at energy scales ranging from lattice vibrations to crystal defects to high-energy collisions. A rigorous method to objectively determine the shape of an interatomic potential over all length scales is introduced by building upon a charged-ion generalization of the well-known Ziegler-Biersack-Littmark universal potential that provides the short- and long-range limiting behavior of the potential. At intermediate ranges the potential is smoothly adjusted by fitting to ab initio data. Our formalism provides a complete description of the interatomic potentials that can be used at any energy scale, and thus, eliminates the inherent ambiguity of splining different potentials generated to study different kinds of atomic-materials behavior. We exemplify the method by developing rigid-ion potentials for uranium dioxide interactions under conditions ranging from thermodynamic equilibrium to very high atomic-energy collisions relevant for fission events.

GULP (2011--Tiwary-P--MOx--GULP--ipr1)
Notes: These files were posted on 17 June 2011 with the approval of Pratyush Tiwary and Axel van de Walle (California Institute of Technology). 30 Jan. 2012 Update: These files are identified as having problems with thermal expansion in UO2 and are superseded by the next GULP implementation below.
File(s): superseded


GULP (2011--Tiwary-P--MOx--GULP--ipr2)
Notes: 30 Jan. 2012 Update: These files (version 2.0) were provided by Pratyush Tiwary (California Institute of Technology) and posted with his permission. According to him, this version corrects the "U-U interaction term (truncated at 4 Angstroms) to resolve problems with thermal expansion in UO2." Additional information is located in readme_v2.txt
File(s):
 
Citation: L.C. Erhard, J. Rohrer, K. Albe, and V.L. Deringer (2022), "A machine-learned interatomic potential for silica and its relation to empirical models", npj Computational Materials, 8(1), 90. DOI: 10.1038/s41524-022-00768-w.
Abstract: Silica (SiO2) is an abundant material with a wide range of applications. Despite much progress, the atomistic modelling of the different forms of silica has remained a challenge. Here we show that by combining density-functional theory at the SCAN functional level with machine-learning-based interatomic potential fitting, a range of condensed phases of silica can be accurately described. We present a Gaussian approximation potential model that achieves high accuracy for the thermodynamic properties of the crystalline phases, and we compare its performance (and performance-cost trade-off) with that of multiple empirically fitted interatomic potentials for silica. We also include amorphous phases, assessing the ability of the potentials to describe structures of melt-quenched glassy silica, their energetic stability, and the high-pressure structural transition to a mainly sixfold-coordinated phase. We suggest that rather than standing on their own, machine-learned potentials for silica may be used in conjunction with suitable empirical models, each having a distinct role and complementing the other, by combining the advantages of the long simulation times afforded by empirical potentials and the near-quantum-mechanical accuracy of machine-learned potentials. This way, our work is expected to advance atomistic simulations of this key material and to benefit further computational studies in the field.

Notes: The potential was designed for crystalline, amorphous and liquid silica and shows also good behavior for certain high-pressure phases. It is not tested for silica surfaces and non stoichiometric phases (non SiO2).

See Computed Properties
Notes: These files were provided by Linus Erhard on Nov 1, 2022, and are alternatively available at the links listed below. For running the potential the QUIP package within LAMMPS is necessary. The file pot.in gives an example of the LAMMPS inputs to use to run this potential. Alternatively, the potential can be used in a python-ase interface called quippy.
File(s): Link(s):
zenodo, includes training data https://doi.org/10.5281/zenodo.6353684

Citation: E. Lee, K.-R. Lee, M.I. Baskes, and B.-J. Lee (2016), "A modified embedded-atom method interatomic potential for ionic systems: 2NNMEAM+Qeq", Physical Review B, 93(14), 144110. DOI: 10.1103/physrevb.93.144110.
Abstract: An interatomic potential model that can simultaneously describe metallic, covalent, and ionic bonding is suggested by combining the second nearest-neighbor modified embedded-atom method (2NNMEAM) and the charge equilibration (Qeq) method, as a further improvement of a series of existing models. Paying special attention to the removal of known problems found in the original Qeq model, a mathematical form for the atomic energy is newly developed, and carefully selected computational techniques are adapted for energy minimization, summation of Coulomb interaction, and charge representation. The model is applied to the Ti-O and Si-O binary systems selected as representative oxide systems for a metallic element and a covalent element. The reliability of the present 2NNMEAM+Qeq potential is evaluated by calculating the fundamental physical properties of a wide range of titanium and silicon oxides and comparing them with experimental data, density functional theory calculations, and other calculations based on (semi-)empirical potential models.

hybrid/overlay coul/streitz meam (2016--Lee-E--Si-O--LAMMPS--ipr1)
See Computed Properties
Notes: These files were obtained from http://cmse.postech.ac.kr/home_2nnmeam, accessed Nov 9, 2020.More information on using the 2NNMEAM-QEQ potentials can be found at https://cmse.postech.ac.kr/lammps/140341.
File(s):
Citation: S. Munetoh, T. Motooka, K. Moriguchi, and A. Shintani (2007), "Interatomic potential for Si-O systems using Tersoff parameterization", Computational Materials Science, 39(2), 334-339. DOI: 10.1016/j.commatsci.2006.06.010.
Abstract: A parameter set for Tersoff potential has been developed to investigate the structural properties of Si-O systems. The potential parameters have been determined based on ab initio calculations of small molecules and the experimental data of α-quartz. The structural properties of various silica polymorphs calculated by using the new potential were in good agreement with their experimental data and ab initio calculation results. Furthermore, we have prepared SiO2 glass using molecular dynamics (MD) simulations by rapid quenching of melted SiO2. The radial distribution function and phonon density of states of SiO2 glass generated by MD simulation were in excellent agreement with those of SiO2 glass obtained experimentally.

LAMMPS pair_style tersoff (2007--Munetoh-S--Si-O--LAMMPS--ipr1)
See Computed Properties
Notes: This file was created and verified by Lucas Hale. The parameter values are comparable to the SiO.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.Q. Broughton, C.A. Meli, P. Vashishta, and R.K. Kalia (1997), "Direct atomistic simulation of quartz crystal oscillators: Bulk properties and nanoscale devices", Physical Review B, 56(2), 611-618. DOI: 10.1103/physrevb.56.611.
Abstract: Current experimental research aims to reduce the size of quartz crystal oscillators into the submicrometer range. Devices then comprise multimillion atoms and operating frequencies will be in the gigahertz regime. Such characteristics make direct atomic scale simulation feasible using large scale parallel computing. Here, we describe molecular-dynamics simulations on bulk and nanoscale device systems focusing on elastic constants and flexural frequencies. Here we find (a) in order to achieve elastic constants within 1% of those of the bulk requires approximately one million atoms; precisely the experimental regime of interest; (b) differences from continuum mechanical frequency predictions are observable for 17 nm devices; (c) devices with 1% defects exhibit dramatic anharmonicity. A subsequent paper describes the direct atomistic simulation of operating characteristics of a micrometer scale device. A PAPS cosubmission gives algorithmic details.

LAMMPS pair_style vashishta (1997--Broughton-J-Q--Si-O--LAMMPS--ipr1)
See Computed Properties
Notes: This file was taken from the August 22, 2018 LAMMPS distribution.
File(s):
Citation: A. Nakano, R.K. Kalia, and P. Vashishta (1994), "First sharp diffraction peak and intermediate-range order in amorphous silica: finite-size effects in molecular dynamics simulations", Journal of Non-Crystalline Solids, 171(2), 157-163. DOI: 10.1016/0022-3093(94)90351-4.
Abstract: Large-scale molecular dynamics simulations of amorphous silica are carried out on systems containing up to 41472 particles using an effective interatomic potential consisting of two-body and three-body covalent interactions. The intermediate-range order represented by the first sharp diffraction peak (FSDP) in the neutron static structure factor shows a significant dependence on the system size. Correlations in the range 0.4–1.1 nm are found to play a vital role in determining the shape of the FSDP correctly. The calculated structure factor for the largest system is in excellent agreement with neutron diffraction experiments, including the height of the FSDP.

LAMMPS pair_style vashishta (1994--Nakano-A--Si-O--LAMMPS--ipr1)
See Computed Properties
Notes: This file was taken from the August 22, 2018 LAMMPS distribution.
File(s):
Citation: P. Vashishta, R.K. Kalia, J.P. Rino, and I. Ebbsjö (1990), "Interaction potential for SiO2: A molecular-dynamics study of structural correlations", Physical Review B, 41(17), 12197-12209. DOI: 10.1103/physrevb.41.12197.
Abstract: An interaction potential consisting of two-body and three-body covalent interactions is proposed for SiO2. The interaction potential is used in molecular-dynamics studies of structural and dynamical correlations of crystalline, molten, and vitreous states under various conditions of densities and temperatures. The two-body contribution to the interaction potential consists of steric repulsion due to atomic sizes, Coulomb interactions resulting from charge transfer, and charge-dipole interaction to include the effects of large electronic polarizability of anions. The three-body covalent contributions include O-Si-O and Si-O-Si interactions which are angle dependent and functions of Si-O distance. In lattice-structure calculations with the total potential function, α-cristobalite and α-quartz are found to have the lowest and almost degenerate energies, in agreement with experiments. The energies for β-cristobalite, β-quartz, and keatite are found to be higher than those for α-cristobalite and α-quartz. Molecular-dynamics calculations with this potential function correctly describe the short- and intermediate-range order in molten and vitreous states.\nIn the latter, partial pair-distribution functions give Si-O, O-O, and Si-Si bond lengths of 1.62, 2.65, and 3.05 Å, respectively. The vitreous state consists of nearly ideal Si(O1/2)4 tetrahedra in corner-sharing configurations. The Si-O-Si bond-angle distribution has a peak at 142° and a full width at half maximum (FWHM) of 25° in good agreement with nuclear magnetic resonance experiments. The calculated static structure factor is also in agreement with neutron-diffraction experiments. Partial static structure factors reveal that intermediate-range Si-Si, O-O, and Si-O correlations between 4 and 8 Å give rise to the first sharp diffraction peak (FSDP). The FSDP is absent in charge-charge structure factor, which indicates that charge neutrality prevails over length scales between 4 and 8 Å. Dynamical correlations in vitreous and molten states, phonon densities of states of crystalline and vitreous SiO2, infrared spectra of crystalline, vitreous and molten states, isotope effect, distribution of rings and their structure in molten and vitreous states, and structural transformations at high pressures will be discussed in subsequent papers.

LAMMPS pair_style vashishta (1990--Vashishta-P--Si-O--LAMMPS--ipr1)
See Computed Properties
Notes: This file was taken from the August 22, 2018 LAMMPS distribution.
File(s):
 
Citation: E. Lee, K.-R. Lee, M.I. Baskes, and B.-J. Lee (2016), "A modified embedded-atom method interatomic potential for ionic systems: 2NNMEAM+Qeq", Physical Review B, 93(14), 144110. DOI: 10.1103/physrevb.93.144110.
Abstract: An interatomic potential model that can simultaneously describe metallic, covalent, and ionic bonding is suggested by combining the second nearest-neighbor modified embedded-atom method (2NNMEAM) and the charge equilibration (Qeq) method, as a further improvement of a series of existing models. Paying special attention to the removal of known problems found in the original Qeq model, a mathematical form for the atomic energy is newly developed, and carefully selected computational techniques are adapted for energy minimization, summation of Coulomb interaction, and charge representation. The model is applied to the Ti-O and Si-O binary systems selected as representative oxide systems for a metallic element and a covalent element. The reliability of the present 2NNMEAM+Qeq potential is evaluated by calculating the fundamental physical properties of a wide range of titanium and silicon oxides and comparing them with experimental data, density functional theory calculations, and other calculations based on (semi-)empirical potential models.

hybrid/overlay coul/streitz meam (2016--Lee-E--Ti-O--LAMMPS--ipr1)
See Computed Properties
Notes: These files were obtained from http://cmse.postech.ac.kr/home_2nnmeam, accessed Nov 9, 2020.More information on using the 2NNMEAM-QEQ potentials can be found at https://cmse.postech.ac.kr/lammps/140341.
File(s):
Citation: P. Zhang, and D.R. Trinkle (2016), "A modified embedded atom method potential for interstitial oxygen in titanium", Computational Materials Science, 124, 204-210. DOI: 10.1016/j.commatsci.2016.07.039.
Abstract: Modeling oxygen interstitials in titanium requires a new empirical potential. We optimize potential parameters using a fitting database of first-principle oxygen interstitial energies and forces. A new database optimization algorithm based on Bayesian sampling is applied to obtain an optimal potential for a specific testing set of density functional data. A parallel genetic algorithm minimizes the sum of logistic function evaluations of the testing set predictions. We test the transferability of the potential model against oxygen interstitials in HCP titanium, transition barriers between oxygen interstitial sites, and oxygen in the titanium prismatic stacking fault. The potential predicts that the interaction between oxygen and a screw dislocation core is weak and short-ranged.

Notes: Prof. Trinkle said that this potential is specifically intended for dilute oxygen in titanium as there's no oxygen-oxygen interaction. 9 Aug. 2016: the reference information was updated.

MEAM splines (2016--Zhang-P--Ti-O--table--ipr1)
Notes: This file was sent by Prof. Dallas Trinkle (Univ. of Illinois) on 6 Aug. 2016 and posted with his permission. Update 2018-11-06: file format changed to reflect that it does not work with LAMMPS.
File(s): superseded


MEAM splines (2016--Zhang-P--Ti-O--table--ipr2)
Notes: This file was sent by Prof. Dallas Trinkle (Univ. of Illinois) on 9 Aug. 2016 and posted with his permission. This version removes an extra comment line that was not compatible with the LAMMPS MEAM/spline code. Update 2018-11-06: file format changed to reflect that it does not work with LAMMPS (see version below).
File(s): superseded


LAMMPS pair_style meam/spline (2016--Zhang-P--Ti-O--LAMMPS--ipr1)
See Computed Properties
Notes: This file was taken from the August 22, 2018 LAMMPS distribution. It has a slightly different header section from the above versions allowing it to work in the official multi-element meam/spline implementation. This version successfully ran with the stable March 16, 2018 and August 22, 2018 LAMMPS versions.
File(s):
 
Citation: Y. Umeno, A.M. Iskandarov, A. Kubo, and J.M. Albina (2013), "Atomistic Modeling and Ab Initio Calculations of Yttria-Stabilized Zirconia", ECS Transactions, 57(1), 2791-2797. DOI: 10.1149/05701.2791ecst.
Abstract: Though a number of atomistic-model studies of yttria-stabilized zirconia (YSZ) have been reported to elucidate its properties, most of them have employed simple pairwise potential functions to express interactions between atoms, which limits the transferability of the models. We have developed a Tangney-Scandolo dipole model potential for YSZ. Energy, stress and forces on atoms calculated by the ab initio (first-principles) density functional theory are provided as reference data for potential fitting. The developed potential successfully reproduces cubic-tetragonal phase transition at a range of yttria concentration relevant with SOFC application. The potential can well reproduce the barrier energy of oxygen vacancy migration. Molecular dynamics simulations of oxygen diffusion in bulk and at grain boundaries are demonstrated.

Notes: Designed for cubic and tetragonal phases (2-6 mol% yttria) and oxygen migration.

See Computed Properties
Notes: Listing found at https://openkim.org.
Link(s):
 
Citation: P. Erhart, N. Juslin, O. Goy, K. Nordlund, R. Müller, and K. Albe (2006), "Analytic bond-order potential for atomistic simulations of zinc oxide", Journal of Physics: Condensed Matter, 18(29), 6585-6605. DOI: 10.1088/0953-8984/18/29/003.
Abstract: An interatomic potential for zinc oxide and its elemental constituents is derived based on an analytical bond-order formalism. The model potential provides a good description of the bulk properties of various solid structures of zinc oxide including cohesive energies, lattice parameters, and elastic constants. For the pure elements zinc and oxygen the energetics and structural parameters of a variety of bulk phases and in the case of oxygen also molecular structures are reproduced. The dependence of thermal and point defect properties on the cutoff parameters is discussed. As exemplary applications the irradiation of bulk zinc oxide and the elastic response of individual nanorods are studied.

 
Citation: A.E. Thompson, B. Meredig, M. Stan, and C. Wolverton (2014), "Interatomic potential for accurate phonons and defects in UO2", Journal of Nuclear Materials, 446(1-3), 155-162. DOI: 10.1016/j.jnucmat.2013.11.040.
Abstract: We have developed an improved uranium dioxide interatomic potential by fitting to forces, energies, and stresses of first principles molecular dynamics calculations via a genetic algorithm approach called Iterative Potential Refinement (IPR). We compare the defect energetics and vibrational properties of the IPR-fit potential with other interatomic potentials, density functional theory calculations, and experimental phonon dispersions. We find that among previously published potentials examined, there is no potential that simultaneously yields accurate defect energetics and accurate vibrational properties. In contrast, our IPR-fit potential produces both accurate defects and the best agreement with the experimental phonon dispersion and phonon density of states. This combination of accurate properties makes this IPR-fit potential useful for simulating UO2 in high temperature, defect-rich environments typical for nuclear fuel. Additionally, we verify that density functional theory with a Hubbard U correction accurately reproduces the experimentally derived UO2 phonon density of states.

GULP (2014--Thompson-A-E--UO2--GULP--ipr1)
Notes: These parameters were sent by Dr. Alexander Thompson and posted with his approval on 25 Nov. 2014.
Parameters:
O core 1.772816
O shell -3.737358
U core -2.069827
U shell 5.998911
spring
U 115.5906
O 261.0604
buck
U shell O shell 1062.316 0.398196 0.0 0.0 15.0
U shell U shell 183.6 0.420031 0.0 0.0 15.0
buck4
O shell O shell 10402.58 0.238539 81.75059 0.0 1.150671 2.22 2.460169 15.0

Citation: P. Tiwary, A. van de Walle, and N. Grønbech-Jensen (2009), "Ab initio construction of interatomic potentials for uranium dioxide across all interatomic distances", Physical Review B, 80(17), 174302. DOI: 10.1103/physrevb.80.174302.
Abstract: We provide a methodology for generating interatomic potentials for use in classical molecular-dynamics simulations of atomistic phenomena occurring at energy scales ranging from lattice vibrations to crystal defects to high-energy collisions. A rigorous method to objectively determine the shape of an interatomic potential over all length scales is introduced by building upon a charged-ion generalization of the well-known Ziegler-Biersack-Littmark universal potential that provides the short- and long-range limiting behavior of the potential. At intermediate ranges the potential is smoothly adjusted by fitting to ab initio data. Our formalism provides a complete description of the interatomic potentials that can be used at any energy scale, and thus, eliminates the inherent ambiguity of splining different potentials generated to study different kinds of atomic-materials behavior. We exemplify the method by developing rigid-ion potentials for uranium dioxide interactions under conditions ranging from thermodynamic equilibrium to very high atomic-energy collisions relevant for fission events.

Notes: 31 Jan. 2012 Update: This potential has been superseded by the 2011--Tiwary-P-Walle-A-Jeon-B-Gronbech-Jensen-N--MOx interatomic potential.

GULP (2009--Tiwary-P--UO2--GULP--ipr1)
Notes: These were supplied by Pratyush Tiwary and Axel van de Walle (California Institute of Technology) and posted with their approval on 22 June 2011.
File(s): superseded


 
Citation: V. Molinero, and E.B. Moore (2009), "Water Modeled As an Intermediate Element between Carbon and Silicon", The Journal of Physical Chemistry B, 113(13), 4008-4016. DOI: 10.1021/jp805227c.
Abstract: Water and silicon are chemically dissimilar substances with common physical properties. Their liquids display a temperature of maximum density, increased diffusivity on compression, and they form tetrahedral crystals and tetrahedral amorphous phases. The common feature to water, silicon, and carbon is the formation of tetrahedrally coordinated units. We exploit these similarities to develop a coarse-grained model of water (mW) that is essentially an atom with tetrahedrality intermediate between carbon and silicon. mW mimics the hydrogen-bonded structure of water through the introduction of a nonbond angular dependent term that encourages tetrahedral configurations. The model departs from the prevailing paradigm in water modeling: the use of long-ranged forces (electrostatics) to produce short-ranged (hydrogen-bonded) structure. mW has only short-range interactions yet it reproduces the energetics, density and structure of liquid water, and its anomalies and phase transitions with comparable or better accuracy than the most popular atomistic models of water, at less than 1% of the computational cost. We conclude that it is not the nature of the interactions but the connectivity of the molecules that determines the structural and thermodynamic behavior of water. The speedup in computing time provided by mW makes it particularly useful for the study of slow processes in deeply supercooled water, the mechanism of ice nucleation, wetting-drying transitions, and as a realistic water model for coarse-grained simulations of biomolecules and complex materials.

Notes: This potential defines a coarse-grained model of water "mW", where each particle represents a single water molecule.

LAMMPS pair_style sw (2009--Molinero-V--water--ipr-1)
Notes: The parameter file mW.sw was provided by Rodrigo Freitas (Stanford) on Jan 10, 2020. main.pdf contains computed properties and references that show this LAMMPS implementation to give predictions consistent with what is reported in the original paper.
File(s):
Date Created: October 5, 2010 | Last updated: November 18, 2022