Surface lattice Green's functions for high-entropy alloys

TL;DR

This paper develops a method to compute surface Green's functions for high-entropy alloys, enabling better modeling of their elastic surface responses and dislocation behaviors.

Contribution

It introduces a scheme for calculating per-site Green's functions in high-entropy alloys and compares average alloy models with full random alloys.

Findings

Average FeNiCr reproduces mean Green's function of full alloy

Variation is largest near surface Brillouin-zone edge and decays as q^{-2}

Atomistic Green's function approaches continuum near the Gamma point

Abstract

We study the surface elastic response of pure Ni, the random alloy FeNiCr and an average FeNiCr alloy in terms of the surface lattice Green's function. We propose a scheme for computing per-site Green's function and study their per-site variations. The average FeNiCr alloy accurately reproduces the mean Green's function of the full random alloy. Variation around this mean is largest near the edge of the surface Brillouin-zone and decays as $q^{-2}$ with wavevector $q$ towards the $\Gamma$-point. We also present expressions for the continuum surface Green's function of anisotropic solids of finite and infinite thickness and show that the atomistic Green's function approaches continuum near the $\Gamma$-point. Our results are a first step towards efficient contact calculations and Peierls-Nabarro type models for dislocations in high-entropy alloys.