Interband Effects in the Coherent-Potential Approximation. I

Abstract
The coherent-potential approximation is applied to a multiple-band separable-pseudopotential model of an alloy. A general formalism is developed, and the case of a simple one-band model is worked out in detail to illustrate the calculational procedures and to indicate the type of results that may be expected. A subsequent paper will present results for a many-band model.