DETERMINATION OF EFFECTIVE PAIR INTERACTIONS AND SEGREGATION BEHAVIOR AT ALLOY SURFACES

A new method is described to calculate layer-dependent effective pair interactions (EPI's) at alloy surfaces starting from electronic structure data for the constituent species. At a fixed temperature, these EPI's determine the concentration profile parallel to the surface, but in turn are themselves dependent upon the concentration in each layer. Thus they have to be calculated in a combined statistical-mechanical/electronic structure formalism that must be iterated to self-consistency. The method discussed here is based on a real-space configurational averaging procedure applied to a tight-binding Hamiltonian. Results for CucNi1 - c are discussed qualitatively and found to be in good agreement with experiment. © 1990 Pergamon Press plc.