Study on Multiplet Energies of V2+, Cr3+, and Mn4+ in MgO Host Crystal Based on First-Principles Calculations with Consideration of Lattice Relaxation

A comparative study of the multiplet energies of the isoelectronic 3d3 ions in MgO host crystal using the first-principles calculation has been performed by discrete-variational multi-electron method. In this investigation, the effect of lattice relaxation was considered based on geometry optimization using first-principles band-structure calculation. The spin-polarization effect and the effect of Hubbard U were also investigated. The estimated multiplet energies were reasonably well reproduced when we used the optimized cluster with spin-polarization effect and some corrections such as configuration dependent correction and correlation correction. The results also show that the lattice relaxation is important to reproduce the tendency of the transitions from 4A2 state to 4T2 and 4T1a states, while the tendency of the transition from 2E state to 4A2 state is mainly determined by the effect of electron correlation.