| Summary: | In order to predict the LMCT energies for various trivalent transition metal (TM) ions in α-Al2O3 nonempirically, we performed first-principles calculations using TMO69− cluster (TM = Sc3+, Ti3+, V3+, Cr3+, Mn3+, Fe3+) using the Discrete Variational Multi-Electron (DVME) method, which is based on the configuration interaction (CI) approach, and constructed the theoretical energy diagram of the TM 3d levels within the band gap. The theoretical Ligand to Metal Charge Transfer (LMCT) energies were overestimated in the case of simple CI calculations. Therefore in order to overcome this problem we considered the configuration-dependent correction (CDC) and the effect of lattice relaxation based on the Shannon's crystal radii. As a result, the quantitative agreement between the theoretical LMCT energies and the experimental ones was greatly improved and the characteristic dependence of the LMCT energies on atomic species was also successfully reproduced without any experimental parameter. Keywords: First-principles calculation, Charge transfer transition, Transition metal, Multiplet
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