Lattice Relaxation Effects on the Multiplet Energies of Ruby Under Pressure using One-Electron Calculations

Up to recently, it has been difficult to calculate the multiplet energies of compounds using one-electron approach. Since it only considers one electron and one nuclei, the interaction among the electrons are neglected. Previously we have successfully estimated the 2 E→ 4 A 2 (R-line) levels of ruby at 0 pressure using one-electron approach based on one-electron calculation using the first-principles Discrete Variational-Xα (DV-Xα) method. Here we want to perform similar investigation, not only for 0 pressure but up to 110 GPa. We estimated the lattice relaxation effect due to the Cr 3+ substitution and due to the applied pressure by using two different methods i.e., Shannon’s crystal radii and geometry optimizations. Two different types of model cluster consisting of 7 and 63 atoms will be used. The 2 E level is estimated by the barycenter of t 2g 3 configuration which consists of 4 multiplets.