ENHANCED SCREENING OF CORE HOLES AT TRANSITION-METAL SURFACES

Ab initio calculations based on density-functional theory were used to obtain surface core-level shifts for the 4d transition metals and sil ver in the initial-state model and in the full-impurity formulation, g iving an unambiguous separation into initial state and screening terms . This shows that the screening of the core hole is substantially bett er at the surface than in the bulk for a transition metal. For Ag, an opposite and even larger effect is found, showing the central role of d-electron screening in the surface. core-level shift of the transitio n metals.