Ab initio block Lanczos calculation of the Auger spectra of SiF4: Strong two-hole localization effects and foreign imaging

The outer valence double-ionization spectrum of SiF4 is investigated by performing accurate ab initio Green's-function calculations based on a newly implemented block-Lanczos algorithm. An analysis of the double-hole density in the correlated states of SiF42+ proves that pronounced hole-localization phenomena at the fluorine atoms take place in all the final dicationic states of the Auger decay. We discuss how these phenomena are at the origin of the observed fluorine and silicon Auger spectral profiles and, in particular, how they provide a complete and conclusive account of all the peaks appearing in the Si LVV spectrum. Confirming this, a simple convolution of appropriate intra-atomic components of the computed two-hole density distribution is shown to reproduce the measured spectra in every detail. The recently introduced foreign-imaging phenomenon is fully confirmed by the present extended calculations.