Estimate of Mixed-Valency in Transition Metal Oxides from Core Level Photoemission Spectroscopy

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