Effects of Cutoff Functions of Tersoff Potentials on Molecular Dynamics Simulations of Thermal Transport

TL;DR

This paper investigates how different cutoff functions in Tersoff potentials affect molecular dynamics simulations of thermal transport, proposing improved schemes for better accuracy in nanostructured materials.

Contribution

It introduces and evaluates new cutoff schemes for Tersoff potentials to enhance thermal transport simulations in nanostructured materials.

Findings

Existing Tersoff cutoff functions can cause inaccuracies in thermal conductivity calculations.

Proposed cutoff schemes improve the representation of defective and surface regions.

Enhanced schemes lead to more reliable molecular dynamics simulations for nanostructured materials.

Abstract

Past molecular dynamics studies of thermal transport have predominantly used Stillinger-Weber potentials. As materials continuously shrink, their properties increasingly depend on defect and surface effects. Unfortunately, Stillinger-Weber potentials are best used for diamond-cubic-like bulk crystals. They cannot represent the energies of many metastable phases, nor can they accurately predict the energetics of defective and surface regions. To study nanostructured materials, where these regions can dominate thermal transport, the accuracy of Tersoff potentials in representing these structures is more desirable. Based upon an analysis of thermal transport in a GaN system, we demonstrate that the cutoff function of the existing Tersoff potentials may lead to problems in determining the thermal conductivity. To remedy this issue, improved cutoff schemes are proposed and evaluated.