Multiplet calculations of L2,3 x-ray absorption near-edge structures for 3d transition-metal compounds

Abstract

The purpose of this work is to compare the two different procedures to calculate theL2,3 x-ray absorption spectra of transition-metal compounds: (1) the semi-empirical chargetransfer multiplet (CTM) approach and (2) the ab initio configuration-interaction (CI)method based on molecular orbitals. We mainly focused on the difference in the treatmentof ligand field effects and the charge transfer effects in the two methods. The reduction ofmultiplet interactions due to the solid state effects has been found by the ab initio CIapproach. We have also found that the mixing between the original and the chargetransferred configurations obtained by the ab initio CI approach is smaller than thatobtained by the CTM approach, since charge transfer through the covalent bondingbetween metal and ligand atoms has been included by taking the molecular orbitals as thebasis functions.