Surface core-level shifts in bcc transition metals deduced from segregation-energy calculations

It has been shown, using the equivalent-core approximation, that the core-level shift between surface and bulk atoms is equal to the surface segregation energy of an impurity of atomic number Z+1 in a matrix of atomic number Z. In this work, these energies are calculated systematically with the tight-binding method for bcc transition metals, rather than being deduced from thermodynamical data using additional approximations as in previous approaches. The agreement between theory and experiment is significantly improved.