Multiple scattering analysis of Bi(Pb) L3 and O K edges absorption spectra in BaBi(Pb)O3

Single-electron multiple scattering (MS) calculations were performed at the Pb L-3 edge in BaPbO3 and the Bi L-3 and O K edge in BaBiO3 for the large clusters of atoms. Shape of the main peaks in calculated Pb L-3 edge was found to be in a good agreement with the experimental one. However, we found limitations in the single-electron description in BaBiO,: some features at the Bi L-3 and O K edges are not predicted by our calculations. We suggest these features to be related with the many-body excitations in the electronic structure of Bi-O complexes. Interpretation of these features is given based on a 2Bi(+4) --> Bi+3 + Bi+3(L) under bar(2) charge disproportionation model, where, (L) under bar(2) denotes two holes spread on 2p orbitals of six oxygen atoms surrounding the Bi ion.