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

Abstract

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 MO n 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 O h symmetry and n=4 for T d or D 4h 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.