AB-INITIO CALCULATION OF SURFACE CORE-LEVEL SHIFTS FOR TRANSITION-METAL SURFACES

The surface core-level shift (SCLS) for a number of smooth surfaces of 4d-transition metals Mo, Rh, Pd and Ag was calculated within two diff erent approaches using the full-potential LMTO method. The first appro ach, the initial state approximation, estimates the SCLS from the posi tion of the core eigenvalues of atoms at the surface relative to those of the bulk. The second approach treats a surface or bulk atom with a core hole as an impurity by means of a supercell. This approach is in principle exact within the local-density approximation and thus inclu des final-state screening effects. The results show that the screening of the core hole is of different nature for Ag when compared to the t ransition metals.