Theory of x-ray-absorption spectra in PrO2 and some other rare-earth compounds

We analyze rare-earth 3d-core x-ray-absorption spectra (3d XAS) in PrO2, as well as in CeO2, using the impurity Anderson model. It is shown that the interplay between the atomic multiplet coupling and the solid-state hybridization between rare-earth 4f and oxygen 2p states is essential in determining the spectral shape. The calculated spectra are in fair agreement with experimental data which supports the theory that there is a strong mixing between 4f1 and 4f2v in the ground state of PrO2, where v denotes a hole in the oxygen 2p valence band. A theoretical prediction of Pr 4d XAS of PrO2 is also given. Because it contains much structure, experimental determination of this spectrum would be very valuable for the study of mixed-valence compounds.