The multi-reference configuration interaction (MRCI) theory was employed to compute the wavefunction for geometry optimization and vertical excitation energies. For the MRCI calculation, we employed the LUCITA mod-ule for the SF Hamiltonian and the KRCI module for the SO Hamiltonian. In these modules, one can flexibly specify the number of holes in the CI space, and this is called the general-active-space configurationinteraction (GASCI) method. The active space employed in this study is shown in Table . Here, the completeactive-space CI (CASCI) calculation is employed in the space constructed by the t 2g orbitals in the SF or by the u 3/2,g and e 5/2,g orbitals in the SO levels (GAS2), and the two-electron excitation is allowed from the GAS2 space. One-electron excitations from GAS1 and GAS2 (a total of two electrons) are also allowed. The truncation of the virtual orbitals shown in Table II is determined so that the two orbitals are energetically well-separated. The same CI parameters are employed for both SO and SF calculations. The reference orbitals of the MRCI cal- culation are generated with the average-of-configuration Hartree-Fock (AOC-HF) method or the HF method. The detailed parameters are listed in Table .