Configuration averaging calculation of the electronic structure of alloys with arbitrary degrees of long-range order, using the lattice site distribution function

Abstract

We present a new derivation of the t-site scattering operator in terms of the atomic distribution function over lattice sites. The operator path is presented in a form that avoids a double average (over the crystal potential and the t-site operator). In configuration averaging of an over-determined path operator one can introduce sampling coefficients of averages, making it possible to compute changes in symmetry during a structural order-disorder transition. These coefficients reflect the conformity of the atom-sublattice type to the characteristics of the single-electron energy spectrum of the alloy, averaged over the configurations. In this approach the limiting cases are automatically satisfied, and the secular equation reduces to the correct form.