Coherent-potential approximation for liquid metals and amorphous solids. I. Tight-binding model

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Abstract
A tight-binding approach is studied to obtain an approximate solution of the averaged one-particle Green's function for liquid metals and amorphous solids. The short-range atomic correlations are taken into account such that the exclusion effects or the excluded volume effects for atoms are treated in a self-contained manner as proposed by Yonezawa. The approximation is shown to be equivalent to the coherent-potential approximation (CPA) in the sense that it depends on the same physical and mathematical philosophy as the original CPA as well as in the sense that it reduces to the ordinary CPA form when a liquid metal or an amorphous solid is regarded in the limit of a lattice-gas model. The result is also identical with the effective-medium approximation discussed by Roth.