Ab initio surface core-level shifts and surface segregation energies

We have calculated the surface core-level energy shifts of the 4d and 5d transition metals by means of local-density theory and a Green’s-function technique based on the linear muffin-tin orbitals method. Final-state effects are included by treating the core-ionized atom as an impurity located in the bulk and at the surface, respectively. It is shown that the study of surface core-level shifts provides an ideal tool for an accurate determination of the surface segregation energy of a substitutional (Z+1) impurity in a Z metal host (Z denotes atomic number).