Calculation update! New properties have been added to the website for dislocation monopole core structures, dynamic relaxes of both crystal and liquid phases, and melting temperatures! Currently, the results for these properties predominately focus on EAM-style potentials, but the results will be updated for other potentials as the associated calculations finish. Feel free to give us feedback on the new properties so we can improve their representations as needed.
Warning! Note that elemental potentials taken from alloy descriptions may not work well for the pure species. This is particularly true if the elements were fit for compounds instead of being optimized separately. As with all interatomic potentials, please check to make sure that the performance is adequate for your problem.
Citation: R. Gröger, and J. Fikar (2026), "Variable-Charge Model of GaN Within the Streitz-Mintmire Formalism". DOI: 10.2139/ssrn.6118127.
Abstract: An ionic-covalent interatomic potential for GaN is developed by combining the Tersoff potential with electrostatic energy, where charges are determined self-consistently with atomic positions using the charge equilibration method of Streitz and Mintmire. The electrostatic parameters of both elements are derived from their experimental ionization energies and electron affinities, whereas the rates of decay of electron densities are represented by Slater's 1s orbitals and optimized to reproduce net atomic charges obtained from DFT data using the DDEC6 charge partitioning scheme. The incorporation of variable charges resolves a long-standing error in degenerate ground state between the wurtzite and zincblende structures and correctly predicts wurtzite as the ground state. As a consequence, the model predicts finite stacking fault energy, which is shown to be in excellent agreement with DFT calculations. The potential demonstrates transferability across wurtzite, zincblende and rocksalt structures, and yields the formation energies of native point defects consistent with DFT results. Under high pressure, the model predicts a phase transition from wurtzite to rocksalt at 48 GPa, consistent with measurements based on X-ray diffraction.
Notes: This is ionic-covalent potential with self-consistent calculation of ionic charges. The covalent part of bonds is described by the Tersoff potential [J. Nord et al., J. Phys. Cond. Mat. 15, 5649 (2003)] and the electrostatic part is treated within the Streitz-Mintmire method [F. H. Streitz and J. W. Mintmire, Phys. Rev. B 50, 11996 (1994)].
See Computed Properties Notes: These files were provided by Roman Gröger on June 1, 2026, and match with similarly named files in the LAMMPS/potentials directory starting with LAMMPS Feature release 11 February 2026. Using this potential requires LAMMPS Feature release 11 February 2026 or newer. It cannot be used with previous releases, because its implementation required a modification of source code to ensure smooth termination of Coulomb integrals at the cut-off. An example on how to use it is provided in the example/streitz subdirectory of LAMMPS. "GaN.streitz" contains the electrostatic parameters. "GaN.streitz+tersoff.mod" contains the Tersoff parameters in the tersoff/mod format. "scmin.mod" provides a routine for energy minimization with self-consistent charge equilibration that should be used instead of calling minimize. "pot.in" provides an example of the LAMMPS pair_style and pair_coeff lines to use. "in.gan" provides a full example of using the potential. File(s):