MULTIPLE-SCATTERING ANALYSIS OF BI(PB) L-3 AND O K EDGES ABSORPTION-SPECTRA IN BABI(PB)O-3

Single-electron multiple scattering (MS) calculations were performed a t 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 ma ny-body excitations in the electronic structure of Bi-O complexes. Int erpretation of these features is given based on a 2Bi(+4) --> Bi+3 + B i+3(L) under bar(2) charge disproportionation model, where, (L) under bar(2) denotes two holes spread on 2p orbitals of six oxygen atoms sur rounding the Bi ion.