Comparative study of the electronic structure of ordered, partially ordered, and disordered phases of theCu3Au alloy

We present a theoretical study of the electronic structure of ordered, partially ordered, and disordered phases of the ${\mathrm{Cu}}_3$Au alloy using the scalar-relativistic linear muffin-tin orbitals (LMTO) method in conjunction with the coherent-potential approximation. We study the change in the electronic structure caused by the gradual increase of disorder in the alloy by varying the long-range-order parameter S continuously from its maximum (S=1) to the minimum (S=0) possible value. Calculations for the disordered phase (S=0) are performed with and without relaxation of the lattice. The relaxed-lattice calculation takes into account, in an approximate way, the possible deviations from the ideal lattice structure due to the difference in the sizes of the constituent atoms. As a side issue, we address the problem of transferability of the LMTO parameters of the individual alloy components in the pure crystalline phase to the alloy calculation.