Investigation of Ion Dependence of Electronic Structure for 3d3 Ions in Mg2TiO4 Based on First-Principles Calculations

In this work, the local electronic structures around isoelectronic 3d(3) ions such as V2+, Cr3+, and Mn4+ in Mg2TiO4 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 V2+, Cr3+, and Mn4+ doped in Mg2TiO4 were calculated using the discrete variational multi-electron code, which is a configuration-interaction calculation program based on the discrete variational-X alpha 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 (4)A(2) -> T-4(2) (U-band) and (4)A(2) -> T-4(1a) (Y-band) increase as the charge of the transition metal ion increases.