Environment Dependent Interatomic Potential for Bulk Silicon

TL;DR

This paper introduces a new environment-dependent interatomic potential for bulk silicon that accurately models various bonding states and elastic properties with a minimal number of parameters, promising improved simulations of silicon materials.

Contribution

The paper develops a novel functional form for silicon interatomic forces incorporating environment dependence, capturing diverse bonding and elastic behaviors with few parameters.

Findings

Successfully models energetics and elastic properties of diamond silicon

Captures covalent re-hybridization and metallic transition in silicon

Achieves realistic results with computational efficiency comparable to existing models

Abstract

We use recent theoretical advances to develop a new functional form for interatomic forces in bulk silicon. The theoretical results underlying the model include a novel analysis of elastic properties for the diamond and graphitic structures and inversions of ab initio cohesive energy curves. The interaction model includes two-body and three-body terms which depend on the local atomic environment through an effective coordination number. This formulation is able to capture successfully: (i) the energetics and elastic properties of the ground state diamond lattice; (ii) the covalent re-hybridization of undercoordinated atoms; (iii) and a smooth transition to metallic bonding for overcoordinated atoms. Because the essential features of chemical bonding in the bulk are built into the functional form, this model promises to be useful for describing interatomic forces in silicon bulk phases and defects. Although this functional form is remarkably realistic by usual standards, it contains a small number of fitting parameters and requires computational effort comparable to the most efficient existing models. In a companion paper, a complete parameterization of the model is given, and excellent performance for condensed phases and bulk defects is demonstrated.