Cluster effects in multicomponent alloys

A new representation is proposed for the Green's function of a disordered multicomponent substitutional alloy. By means of this representation the $1$-, $2$-, etc., lattice contributions to the Green's function can be readily separated in the corresponding equations. Using the representation, it is possible to obtain general expressions for the configuration-averaged Green's function with allowance for electron scattering by clusters of an arbitrary number of atoms. The calculations are made in a fairly general model of a substitutional alloy. Equations are also found for the vertex paths, and the conditions are investigated under which the approximate expressions for the Green's functions and the vertices satisfy the Ward identity.