# Thermal vacancy formation energies of random solid solutions

## TL;DR

This paper introduces a combined computational approach to efficiently calculate thermal vacancy formation energies in random solid solutions, accounting for local atomic environments, temperature, strain, and magnetism effects.

## Contribution

It presents a novel method combining coherent potential approximation and supercell-local cluster expansion for calculating VFEs in disordered alloys.

## Key findings

- Mean VFE increases with temperature.
- VFE decreases under in-plane tensile and compressive strains.
- Magnetic excitation further reduces VFE.

## Abstract

Vacancy mechanism plays a dominant role in the atomic migration when a close-packed disordered alloy undergoes ordering transition. However, the calculation of thermal vacancy formation energies (VFEs) of random solid solutions is usually cumbersome due to the difficulty in considering various local atomic environments. Here, we propose a transparent way that combines coherent potential approximation and supercell-local cluster expansion to investigate VFEs of random solid solutions. This method is used to study the effects of temperature, strain and magnetism on the VFEs of random A1-FePt alloy. The results show that the mean VFE increases with increasing temperature, decreases under (001) in-plane tensile and compressive strains, and can be further reduced by the magnetic excitation. These effects are explained by discussing the dependence of VFE on local atomic environments and the overall bond strength within.