Amorphous silica modeled with truncated and screened Coulomb interactions: A molecular dynamics simulation study

TL;DR

This study demonstrates that truncated and screened Coulomb interactions, such as the Wolf method and Yukawa potential, can effectively model amorphous silica in molecular dynamics simulations, reducing computational cost while maintaining accuracy.

Contribution

The paper introduces and compares finite-range Coulomb interaction models for silica, showing they can replace traditional Ewald summation with minimal loss of accuracy.

Findings

Wolf method with r_c ~ 10 Å matches Ewald results

Lower cutoffs slightly accelerate dynamics and alter structure

Yukawa potential requires larger cutoffs for similar accuracy

Abstract

We show that finite-range alternatives to the standard long-range BKS pair potential for silica might be used in molecular dynamics simulations. We study two such models that can be efficiently simulated since no Ewald summation is required. We first consider the Wolf method, where the Coulomb interactions are truncated at a cutoff distance r_c such that the requirement of charge neutrality holds. Various static and dynamic quantities are computed and compared to results from simulations using Ewald summations. We find very good agreement for r_c ~ 10 Angstroms. For lower values of r_c, the long--range structure is affected which is accompanied by a slight acceleration of dynamic properties. In a second approach, the Coulomb interaction is replaced by an effective Yukawa interaction with two new parameters determined by a force fitting procedure. The same trend as for the Wolf method is seen. However, slightly larger cutoffs have to be used in order to obtain the same accuracy with respect to static and dynamic quantities as for the Wolf method.