A Modified Stillinger-Weber Potential for TlBr, and Its Polymorphic Extension

Abstract

TlBr is promising for γ-and x-radiation detection, but suffers from rapid performance degradation under the operating external electric fields. To enable molecular dynamics (MD) studies of this degradation, we have developed a Stillinger-Weber type of TlBr interatomic potential. During this process, we have also addressed two problems of wider interests. First, the conventional Stillinger-Weber potential format is only applicable for tetrahedral structures (e.g., diamond-cubic, zinc-blende, or wurtzite). Here we have modified the analytical functions of the Stillinger-Weber potential so that it can now be used for other crystal structures. Second, past modifications of interatomic potentials cannot always be applied by a broad community because any new analytical functions of the potential would require corresponding changes in the molecular dynamics codes. Here we have developed a polymorphic potential model that simultaneously incorporates Stillinger-Weber, Tersoff, embedded-atom method, and any variations (i.e., modified functions) of these potentials. We have implemented this polymorphic model in MD code LAMMPS, and demonstrated that our TlBr potential enables stable MD simulations under external electric fields.

Coarse-Grained Simulation of CaCO3 Aggregation and Crystallization Made Possible by Nonbonded Three-Body Interactions

“…The function in eq 3 was implemented in the form of eq 4 as a tabulated three-body potential using the implementation of the polymorphic extension of the Stillinger−Weber potential by Zhou et al 23 in LAMMPS.…”

“…Therefore, a new type of three-body term needed to be introduced. Starting from the ansatz of a periodic cosine potential, as used in the DREIDING force field, we complemented a Stillinger–Weber like three-body term with an angle-dependent term that was specifically modified to be capable of describing the angles between ion sites in calcite, in particular, allowing for multiple minima; see eq . The function in eq was implemented in the form of eq as a tabulated three-body potential using the implementation of the polymorphic extension of the Stillinger–Weber potential by Zhou et al in LAMMPS. These three-body interactions were used as short-range energy penalty functions in conjunction with the above mentioned Lennard-Jones or Buckingham two-body interaction potentials.…”

Effect of Substrate Surface on Deposition of AlGaN: A Molecular Dynamics Simulation

“…The Large-scale Atomic/Molecular Massively Parallel Simulator (LAMMPS) [24] with SW potential [25,26] has been adopted. So far, there have been many potentials developed for GaN [27][28][29] and AlN [30,31], but few potentials describe the interatomic potentials of Al-Ga-N. In this work, the SW potential is chosen to describe the interatomic interaction in Al-Ga-N.…”