Electronic structure of bulk and surface disordered alloys

Abstract

Electronic densities of states of bulk and cleaved binary alloys are determined through a tight-binding model, using a continued fraction technique and a computer simulation on clusters of several thousands of atoms. Results are presented for nondegenerate bands and simple and face centred cubic lattices. They are compared with the coherent potential approximation (CPA) and Bethe-Peierls approximation (BPA). The method can deal with cleaved binary alloys and also non-homogeneous alloys, and an example of a cleaved alloy with surface segregation is given. The surface density of states is shown to be strongly sensitive to the composition of the first layer and this could be an important factor in studying surface segregation.