Spectral density of states in disordered beta brass

Abstract

The spectral density of states for electrons in disordered β brass has been determined by calculating the T matrix for the system. The geometric approximation introduced by Beeby has been invoked to sum the infinite series expressing the total T matrix in terms of the t matrices for the individual scatters. Beeby's procedure is extended to take account of the short-range order present in the alloy, and it results in the introduction of incomplete Green's functions of the form previously used by the authors in another approach for calculating the electronic spectrum of disordered alloys. Information about the short-range order obtained from neutron-scattering measurements is used to evaluate the incomplete Green's functions as well as the crystal potentials for the constituents. Model potentials of the form used by Soven are employed to facilitate the calculation of the t matrices. The distinction between the constituents is retained. We have computed the spectral density of states for β brass at the symmetry points Γ, H, P, and N of the Brillouin zone. The results are used to predict the flatness of the Fermi surface, which compares well with the speculative interpretation by Moss of the neutron-scattering data.