All-electron CI calculations of 3d transition-metal L_2,3 XANES using zeroth-order regular approximation for relativistic effects

X-ray-absorption near-edge structures (XANES) at 3d transition-metal (TM) L_2,3 edges are computed using the all-electron configuration interaction (CI) method. Slater determinants for the CI calculations are composed of molecular orbitals obtained by density functional theory (DFT) calculations of model clusters. Relativistic effects are taken into account by the zeroth-order regular approximation (ZORA) using two-component wavefunctions. The theoretical spectra are found to be strongly dependent on the quality of the one-electron basis functions. On the other hand, a different choice of the exchange–correlation functionals for the DFT calculations does not exhibit visible changes in the spectral shape. Fine details of multiplet structures in the experimental TM L_2,3 XANES of MnO, FeO and CoO are well reproduced by the present calculations when the one-electron basis functions are properly selected. This is consistent with our previous report showing good agreement between theoretical and experimental TM L_2,3 XANES when four-component relativistic wavefunctions were used.