Generalized Locator—Coherent-Potential Approach to Binary Alloys

Abstract

The electronic structure of binary alloys is discussed for a system in which both the atomic energy levels and the hopping integrals are random quantities. This paper is a detailed study of the generalization of the coherent-potential approximation (CPA) introduced earlier by the present authors. We show that a locator description provides a particularly suitable formalism for setting up this generalized problem and how, with the aid of a simple device, configuration averaging may be performed by the use of established techniques. The approximation used is, as in the case of the usual CPA, a single-site one. Three self-consistent equations are obtained that must be solved simultaneously; these replace the single CPA equation. Numerical results are displayed for a series of alloys, and a discussion of certain aspects of the theory, such as its moment-preserving properties, is also included.