Cluster coherent-potential approximation in the tight-binding linear-muffin-tin-orbital formalism

We present a method for the determination of the electronic structure of random alloys within the self-consistent cluster coherent-potential approximation in the tight-binding linear-muffin-tin-orbital method. This formalism combines the simplicity of the tight-binding linear-muffin-tin-orbital scheme with the cluster coherent-potential approximation to determine the effective medium self-consistently. This approximation is analytic and guarantees non-negative and single-valued density of states at all energies. We have derived an expression for the configuration-averaged Green's function from which one can determine various electronic properties of the alloys, in particular, the charge densities, which are needed for charge self-consistent calculations. We have applied this formalism to an s-band model and found that cluster effects could cause significant changes in the density of states.