Investigation of the nonlocal coherent-potential approximation

TL;DR

This paper presents an analytical and numerical study of the nonlocal coherent-potential approximation (NLCPA), comparing it with other methods for modeling electronic structures in disordered systems, highlighting its systematic improvements and symmetry preservation.

Contribution

It provides the first detailed analytical and numerical analysis of NLCPA for a 1D model, comparing its performance with ECM and MCPA methods.

Findings

NLCPA offers systematic corrections to CPA

NLCPA preserves lattice symmetry

Comparative analysis shows NLCPA's advantages

Abstract

Recently the nonlocal coherent-potential approximation (NLCPA) has been introduced by Jarrell and Krishnamurthy for describing the electronic structure of substitutionally disordered systems. The NLCPA provides systematic corrections to the widely used coherent-potential approximation (CPA) whilst preserving the full symmetry of the underlying lattice. Here an analytical and systematic numerical study of the NLCPA is presented for a one-dimensional tight-binding model Hamiltonian, and comparisons with the embedded cluster method (ECM) and molecular coherent potential approximation (MCPA) are made.