Correlation correction to the free energy for the ising model of a binary alloy

Abstract

We consider correlation corrections to the free energy of the Ising model of a binary solid solution. The correlation free energy is represented in the form of a high-temperature series, in which only the leading terms in the parameter 1/z are retained, where z is the number of lattice sites inside the effective interaction sphere of the interatomic potential. In some cases the series can be assumed and an explicit formula can be obtained for the correlation corrections. As one of the consequences of our results, we obtain a correction to the mean field theory expression for the order-disorder transition point.