Electronic properties of an alloy with off-diagonal disorder

Abstract

Densities of states and spectral functions are computed for relatively large (∼ 8000 atom) models of an alloy with off-diagonal disorder. A nearest-neighbor tight-binding electronic Hamiltonian is assumed. the numerical results are compared with those obtained from calculations based on the coherent-potential approximation (CPA) with the "additive limit." The overall agreement is quite satisfactory. In particular, the two approaches yield remarkably similar descriptions of the minority states in the case of purely off-diagonal scattering. As expected, the substructure in the electronic spectrum due to minority clusters is not reproduced by the CPA.