Density-functional theory for random alloys: Total energy within the coherent-potential approximation.

A density-functional--based theory is developed for calculation of the total energy and pressure of random substitutional alloys within the Korringa-Kohn-Rostoker coherent-potential approximation. The theory is used to calculate the concentration variation of the equilibrium lattice spacing of ..cap alpha..-phase Cu/sub c/Zn/sub 1-c/ alloys. We find, in agreement with experiment, that the variation is almost linear and that it deviates from Vegard's rule.