Toward a unified approach to the study of metallic alloys: Application to the phase stability of Ni-Pt

We present the first implementation of a unified approach to the study of alloys, using the atomic-sphere approximation formulation of the Korringa-Kohn-Rostoker coherent potential approximation method [P. P. Singh and A. Gonis, Phys. Rev. B 48, 1989 (1993)], which allows the treatment of the disordered alloy and of the ordered alloys on an equal footing. We apply this method to the study of the phase stability of the Ni-Pt alloy and resolve a number of discrepancies that have arisen in recent studies of this system.