Electronic structures of 3d transition metal (Ti–Cu) oxides probed by a core hole Original Research Article

Electronic structures of various 3d transition metal oxides are calculated using the spin-unrestricted discrete-variational (DV) Hartree–Fock–Slater (Xα) method for the ground state and 1s−1 core hole state. Model clusters MOn are used in place of calculating infinite size solids, where M is the transition metal elements from Ti (Z=22) to Cu (Z=29) and n the coordination number of oxygen; n=6 for Oh symmetry and n=4 for Td or D4h symmetry. The calculated results indicate that the number of unpaired 3d electrons reduces in the creation of the core hole for late transition metal compounds, i.e. do not represent the ground-state spin state for these compounds, but conserves for early transition metal compounds. These results provide theoretical basis on the validity of spin selective X-ray absorption spectroscopy for early transition metal compounds by using the high-resolution X-ray fluorescence yield method, and theoretical basis on the validity or nonvalidity of spin state analysis using core-level spectroscopy, such as X-ray emission, X-ray absorption, and photoelectron spectroscopies. It is also found that the spin of a class of compounds sometimes flips in the creation of the core hole.