Controversy over Elastic Constants Based on Interatomic Potentials

TL;DR

This paper clarifies the controversy over elastic constant constraints imposed by interatomic potentials, showing that some potentials do not impose these constraints and that R-EAM potentials eliminate them entirely.

Contribution

It identifies the necessary conditions for elastic constant constraints and demonstrates that R-EAM potentials remove these constraints.

Findings

Some EAM potentials do not impose elastic constant constraints.

The three constraints are eliminated by using R-EAM potentials.

The necessary condition for constraints is physically necessary.

Abstract

A controversy exists among literature reports of constraints on elastic constants. In particular, it has been reported that embedded atom method (EAM) potentials generally impose three constraints on elastic constants of crystals that are inconsistent with experiments. However, it can be shown that some EAM potentials do not impose such constraints at all. This paper first resolves this controversy by identifying the necessary condition when the constraints exist and demonstrating the condition is physically necessary. Furthermore, this paper reports that these three constraints are eliminated under all conditions, by using response EAM (R-EAM) potentials.