Electronic structure of random binary alloys beyond the single-site approximation

Abstract

We study the influence of short-range order (SRO) and correlated scattering by pairs of atoms on the electronic structure of random binary alloys. Our approach is based on the gamma expansion method (GEM) proposed by Tokar, and implemented within a tight-binding linear-muffin-tin orbital (TB-LMTO) formulation of the (single-site) coherent potential approximation (SCPA) which approximately accounts for geometric relaxation. Results are presented for ${\mathrm{Ag}}_{0.87}{\mathrm{Al}}_{0.13},$ in which the SRO has recently been measured, and ${\mathrm{Cu}}_{0.715}{\mathrm{Pd}}_{0.285},$ for which older data exist, and where lattice relaxation effects play an important role. In both cases we find that the density of states (DOS) of the system is only weakly affected by the SRO. The applicability of the GEM to a first principles determination of the degree of SRO is briefly discussed.