Among previous studies, 4c-SAOP consistently yields the highest excitation energy values for all Ω states, while 4c-IHFSCCSD produces the lowest. The results of SO-CASPT2 and SO-EOM-CCSD agree well with each other and fall between those of 4c-SAOP and 4c-IHFSCCSD. In the present study, RASCI estimates higher excitation energies for all Ω states, whereas RASPT2 values decrease and align more closely with those reported in previous studies. This indicates the importance of including dynamic electron correlation in RASPT2.