The parameters entering the effective Ising model of disordered alloys with nonuniform composition at the sample surface are derived within the framework of the generalized perturbation method. The tight-binding version of the linear-muffin-tin-orbital method and its generalization to inhomogeneous alloys is used to describe the electronic structure in the local-density approximation, while the semi-infinite nature of the problem is included via the surface Greens-function approach. The method is applied to evaluate the site-diagonal terms of the Ising model as well as the effective interatomic interactions between sites within and between top layers up to the fourth-nearest neighbors of the fcc (001) face of the transition-metal alloys Pd50Rh50 and Ag50Pd50.
ASJC Scopus subject areas
- Condensed Matter Physics