Nonlocal spectral properties of disordered alloys

TL;DR

This paper introduces a new method for calculating detailed spectral functions in disordered alloys using a nonlocal CPA approach, revealing phenomena like smeared electronic topological transitions.

Contribution

The paper presents a novel approach combining periodic and anti-periodic solutions within NLCPA to accurately compute spectral functions and bulk properties for small clusters.

Findings

Successfully computes fully k-dependent spectral functions.

Reveals smeared electronic topological transition in 2D alloy.

Provides a more accurate description of disordered systems.

Abstract

A general method is proposed for calculating a fully k-dependent, continuous, and causal spectral function A(k,E) within the recently introduced nonlocal version of the coherent-potential approximation (NLCPA). The method involves the combination of both periodic and anti-periodic solutions to the associated cluster problem and also leads to correct bulk quantities for small cluster sizes. We illustrate the method by investigating the Fermi surface of a two-dimensional alloy. Dramatically, we find a smeared electronic topological transition not predicted by the conventional CPA.