Relaxation and screening in Auger emission: an explanation for the changes from bandlike to quasi-atomiclike CVV Auger spectra across the transition metal series

Supercell method is used to study the relaxation and screening effects during the Auger transition in metals. Our consideration is based on the assumption that when a core-hole exists long enough before the Auger transition occurs, the occupied valence states relax to screen the core-hole which results in a redistribution of the valence electrons, in particular within the atom that contains the core-hole. In order to make the interaction between the core-holes sited at different atoms negligible, the real metal is simulated by supercells repeated periodically. In each supercell one atom is considered to have a core-hole and many others without core-hole. The electronic states concerned by the Auger transition are calculated by the self-consistent fullpotential linearized augmented plane wave (FLAPW) method. The occurrence of both bandlike and quasi-atomiclike Auger spectra across transition metal series is related clearly to the different responses of these metals to the existence of a core-hole depending on whether their d-bands are partially or completely filled. As examples, L3VV and M1VV Auger spectral profiles of Cu have been calculated in a reasonably well agreement with experiment. PACS number(s): 79.20.Fv, 71.15.Ap, 71.20.Be Typeset using REVTEX