Ab initio Approaches to High Entropy Alloys: A Comparison of CPA, SQS, and Supercell Methods

TL;DR

This study compares different computational methods for modeling the electronic properties of a specific high entropy alloy, finding consistent results across methods and no magnetic moments, with potential superconductivity at low temperatures.

Contribution

It provides a detailed comparison of CPA, SQS, and supercell methods for high entropy alloys within density functional theory, including charge screening effects.

Findings

CPA and supercell methods yield similar ground state properties.

No evidence of magnetic moments in the alloy.

Potential superconductivity below approximately 9K.

Abstract

We present a comparative study of different modeling approaches to the electronic properties of the $\textrm{Hf}_{0.05}\textrm{Nb}_{0.05}\textrm{Ta}_{0.8}\textrm{Ti}_{0.05}\textrm{Zr}_{0.05}$ high entropy alloy. Common to our modeling is the methodology to compute the one-particle Green's function in the framework of density functional theory. We demonstrate that the special quasi-random structures modeling and the supercell, i.e. the locally self-consistent multiple-scatering methods provide very similar results for the ground state properties such as the spectral function (density of states) and the equilibrium lattice parameter. To reconcile the multiple-scattering single-site coherent potential approximation with the real space supercell methods, we included the effect of screening of the net charges of the alloy components. Based on the analysis of the total energy and spectral functions computed within the density functional theory, we found no signature for the long-range or local magnetic moments formation in the $\textrm{Hf}_{0.05}\textrm{Nb}_{0.05}\textrm{Ta}_{0.8}\textrm{Ti}_{0.05}\textrm{Zr}_{0.05}$ high entropy alloy, instead we find possible superconductivity below $\sim 9$K.