Augmented-Plane-Wave Virtual-Crystal Approximation

Abstract

A new perfect-crystal technique based on the augmented-plane-wave (APW) method and the virtual-crystal approximation (VCA) is developed to treat random three-dimensional alloys and partially vacant crystals. The APW VCA is superior to existing perfect-crystal techniques and is a degenerate form of the $t$-matrix approximation of Korringa and Beeby. An average muffin-tin potential for alloys is proposed. Together with the APW VCA, this model potential can be used to compute band structure and density of states of substitutional alloys. The method of obtaining the density of states from the APW-VCA band structure is more complicated than in perfect crystals.