Investigation of Ion Dependence of Electronic Structure for 3d~3 Ions in Mg_2TiO_4 Based on First-Principles Calculations

摘要

In this work, the local electronic structures around isoelectronic 3d~3 ions such as V~(2+), Cr~(3+), and Mn~(4+) in Mg_2TiO_4 crystals were investigated based on first-principles configuration-interaction calculations. The factors to determine tendencies of the crystal field splitting and the multiplet energy among them were analyzed in detail based on the explicit many-electron wave functions. The multiplet energy levels of V~(2+), Cr~(3+), and Mn~(4+) doped in Mg_2TiO_4 were calculated using the discrete variational multi-electron code, which is a configuration-interaction calculation program based on the discrete variational-Xa method. Overall, the results show that only the calculation with consideration of the lattice relaxation effect can provide a reasonable tendency, where the multiplet energies of ~4A_2 → ~4T_2 (U-band) and ~4A_2 → ~4T_(1a) (Y-band) increase as the charge of the transition metal ion increases.