Hybrid expansions for local structural relaxations

TL;DR

This paper introduces a hybrid modeling approach combining pair potentials and cluster expansion to improve the accuracy of predicting phase stability in substitutional alloys, accounting for structural relaxations and ordering effects.

Contribution

It presents a novel hybrid expansion method that integrates pair potentials with cluster expansion for better modeling of alloy energetics and phase stability.

Findings

Enhanced modeling of structural relaxations in alloys

Improved phase stability predictions from first-principles

Effective incorporation of atomic relaxations and ordering effects

Abstract

A model is constructed in which pair potentials are combined with the cluster expansion method in order to better describe the energetics of structurally relaxed substitutional alloys. The effect of structural relaxations away from the ideal crystal positions, and the effect of ordering is described by interatomic-distance dependent pair potentials, while more subtle configurational aspects associated with correlations of three- and more sites are described purely within the cluster expansion formalism. Implementation of such a hybrid expansion in the context of the cluster variation method or Monte Carlo method gives improved ability to model phase stability in alloys from first-principles.