SURFACE BINDING-ENERGIES OF ALLOYS - A MANY-BODY APPROACH

The surface binding energy of atoms is a crucial quantity for determining the sputtering behaviour of a sample under energetic atom bombardment. We study the surface binding energy of a binary alloy using a many-body interaction potential of the tight-binding type; analytical calculations are checked against molecular-statics computer simulations. As a result, we find a linear dependence of the surface binding energy of each species on its concentration. Quantitatively, its behaviour can be derived from the properties of the pure substances. The influence of the chemical energies of mixing is only small. These results correspond qualitatively to those of a pair-potential model, which are well known. The differences are of a quantitative nature. While these results have been derived for an undamaged surface, we also discuss the sputtering behaviour under steady-state conditions.