Embedding of cluster models of oxides: Implications for XPS predictions

Abstract

The importance of embedding cluster models of NiO that are used to predict and analyze the Ni 2p XPS spectra in this compound is studied. The XPS obtained with an isolated NiO₆ cluster are compared with those obtained with the cluster embedded in a point charge field designed to reproduce the Madelung potential of the crystal. It is found that there is a remarkable and possibly unexpected similarity between the theoretical XPS spectra with and without point charge embedding. It is believed that this can be expected to be a general conclusion relevant for the XPS of other ionic compounds.