From the gross population, 5d 5/2 (5d 3/2 ) contributes to the u ′ 3/2,g (u 3/2,g ) spinors more significantly. This means that the SO splitting at the atomic orbital level remains even under the ligand field, and the SO splitting changes the degeneracy behavior of the MOs. According to the Mulliken population analysis using the one-component basis sets, the d xy , d yz , and d xz orbitals are distributed to the e 5/2,g and u 3/2,g orbitals, and d x 2 , d y 2 , and d z 2 contribute to u ′ 3/2,g orbitals. Therefore, u ′ 3/2,g orbitals would have similar properties to those of e ′ g orbitals, al-though the assignments are different at the SF and SO levels. In fact, the total gross populations of d orbitals of u ′ 3/2,g and e ′ g have almost the same magnitude.