50, we identify seven MECIs and perform reference calculations using a two-state averaged CASSCF(6e,6o) wavefunction. The entry 5 in Ref. 50 is excluded because it was predicted to be a saddle point in the intersection space. The experimental vertical excitation energy at the D 6h geometry is 4.9 eV, and so XMS is the closest. RMS deviates by 0.2 eV, but a systematic investigation is required to determine which CASPT2 variant yields the best general agreement with experiment.