Electronic structure of disordered binary alloy surfaces in the presence of short-range order within the cluster Bethe lattice approach

Abstract

The authors present here a theory for studying the local electronic structure at the surfaces of a disordered binary alloy in the presence of short-range order (SRO) in the system, the alloy being considered as having Bethe lattice topology. This theory offers a way of going beyond the single-site coherent potential approximation (CPA) by allowing the incorporation of the effects of environmental fluctuations. This method leads to an effective medium for this semiinfinite system which can be obtained in a very elegant way by modifying the CPA effective medium. The well-known limits of complete segregation and binary sequence are exactly obtained and, in the random case, the CPA results for the surfaces are reproduced.