Calculation of X-ray absorption near edge structure of CeO2 using a model cluster

We report result of a first-principle molecular orbital calculation using discrete-variational (DV)-X method on a model of CeO₂ ([CeO₈]¹²⁻), and compare them with experimental date on X-ray absorption-near-edge structure. Even using a small cluster model, we can reproduce the two-peak structure near edge and explain the origin of the peaks. The two-peak structure is relially interpreted from the viewpoint of interactions between atomic orbitals. The theoretical spectra are obtained with the dipole approximation. In addition, we calculate the wave functions, which indicate that the low-energy peak in the two-peak structure originates from a quasi-bound state composed of localized Ce d and O component. The orgin of the high-energy peak is the phase shift between localized Ce d orbital and that of the delocalized standing wave of O atomic orbitals.