Ab initio theory of surface segregation: Self-consistent determination of the concentration profile.

Abstract

Ab-initio studies of surface segregation in alloys are based on the Ising-type Hamiltonian, whose parameters are the effective cluster interactions (ECI). The ECIs for alloy surfaces can be determined by various methods, e.g., by the Connolly-Williams inversion scheme1–3, or by the generalized perturbation method (GPM)4. The GPM relies on the force theorem5, according to which only the band term is mapped onto the Ising Hamiltonian in the bulk case. The case of macroscopically inhomogeneous systems, like disordered surfaces is more complex.