Calculating properties with the polymorphous coherent-potential approximation

The formulas for calculating properties of an alloy such as the density of states, the charge density, and the Bloch spectral density function are der ived from multiple-scattering theory for the polymorphous coherent-potentia l approximation (PCPA). The chemical shifts obtained for three alloy system s using the PCPA, the Korringa-Kohn-Rostoker CPA, and the locally self-cons istent multiple-scattering method are compared with experiment A significan t improvement in the treatment of Coulomb effects is achieved using the PCP A with only a little more computational effort than for the older isomorpho us CPA's.