An averaged cluster approach to including chemical short range order in KKR-CPA

TL;DR

This paper introduces a new averaged cluster method to incorporate chemical short range order into KKR-CPA calculations, improving the modeling of disordered metallic alloys.

Contribution

The paper develops a novel technique to include chemical short range order in KKR-CPA by embedding an averaged cluster, with demonstrated applications to alloy systems.

Findings

Method successfully models SRO effects in alloys

Comparison shows differences between self-consistent and non-self-consistent modes

Code implementation is publicly available

Abstract

The single-site Korringa-Kohn-Rostoker Coherent Potential Approximation (KKR-CPA) ignores short range ordering present in disordered metallic systems. In this paper, we establish a new technique to fix this shortcoming by embedding an averaged cluster that displays chemical short range order (SRO). The degree of SRO can be tuned by externally defined order parameters. This averaged cluster can be embedded in the single site CPA medium, or a self-consistently obtained effective medium that contains SRO information. The validity of this method is demonstrated by applying it to two alloy systems - the CuZn body centered cubic (BCC) solid solution, and AlCrTiV, a four-element BCC high entropy alloy. A comparison between the non-self-consistent and self-consistent modes is also provided for the two above mentioned systems. We make the code available on the internet. Planned extensions to this work are discussed.