Multiplet Energy Level Diagrams for Cr³⁺and Mn⁴⁺in Oxides with OhSite Symmetry Based on First-Principles Calculations

The energy diagram representing the relationship between the multiplet energy levels of Cr 3+ and the Cr-O bond length has been constructed based on first-principles calculation using CrO 6 cluster with O h symmetry. The tendency of the pressure dependence of the R line energy of ruby has been reproduced by calculation considering the configuration-dependent correction and the correlation correction. The results indicated that this tendency is dominated by the effect of correlation correction rather than the effect of covalency. In order to establish guidelines for the theoretical design of novel Mn 4+ -doped oxide phosphors, a similar diagram was also constructed for Mn 4+ based on first-principles calculation using MnO 6 cluster with O h symmetry.