ESTIMATE OF MIXED-VALENCY IN TRANSITION-METAL OXIDES FROM CORE-LEVEL PHOTOEMISSION SPECTROSCOPY

With extensive calculations based on cluster and impurity models, we a nalyse core level photoemission spectra of several transition metal co mpounds. Our results show that the average d-occupancy is determined w ith sufficient accuracy from these spectra, though different interacti on strengths, like U, Delta, and t individually have a very wide range of uncertainties. It is also found that an analysis of core level spe ctra of a stoichiometric compound can provide a good estimate even for the character of doped holes in such systems.