Coupling a reactive potential with a harmonic approximation for atomistic simulations of material failure

TL;DR

This paper introduces a hybrid simulation approach combining reactive and harmonic potentials to efficiently model material failure in molecular dynamics, reducing computational costs while maintaining accuracy in critical regions.

Contribution

The authors develop a method to couple reactive potentials with harmonic approximations, enabling seamless and adaptive simulation of material failure with improved efficiency.

Findings

Accurate energy, geometry, and Hessian reproduction in the ground state.

Effective on-the-fly substitution criterion for reactive potential.

Successful application to graphene failure simulation.

Abstract

Molecular dynamics (MD) simulations involving reactive potentials can be used to model material failure. The empirical potentials which are used in such simulations are able to adapt to the atomic environment, at the expense of a significantly higher computational cost than non-reactive potentials. However, during a simulation of failure, the reactive ability is needed only in some limited parts of the system, where bonds break or form and the atomic environment changes. Therefore, simpler non-reactive potentials can be used in the remainder of the system, provided that such potentials reproduce correctly the behavior of the reactive potentials in this region, and that seamless coupling is ensured at the interface between the reactive and non-reactive regions. In this article, we propose a methodology to combine a reactive potential with a non-reactive approximation thereof, made of a set of harmonic pair and angle interactions and whose parameters are adjusted to predict the same energy, geometry and Hessian in the ground state of the potential. We present a methodology to construct the non-reactive approximation of the reactive potential, and a way to couple these two potentials. We also propose a criterion for on-the-fly substitution of the reactive potential by its non-reactive approximation during a simulation. We illustrate the correctness of this hybrid technique for the case of MD simulation of failure in two-dimensional graphene originally modeled with REBO potential.