Free energy of mixing of an Fe–Co liquid alloy taking into account nondiagonal d−d-electron coupling in the framework of the Willis−Harrison model

Abstract

Within the framework of the Willis−Harrison model, the effect of taking into account d−d-electron couplings nondiagonal in the magnetic quantum number between the neighboring atoms in a transition metal on the partial pair potentials and the free energy of mixing of an Fe–Co liquid alloy near the melting temperature is investigated. It is found that an increase in the fraction of nondiagonal couplings results in a decrease in the depth of the first minimum of the partial pair potentials and in the displacement of its position towards larger r. It is shown that taking this factor into account considerably improves the agreement with experimental data of the concentration dependence of the free energy of mixing of the system under consideration.