Ab initio calculations on excited states of VCH

The ground state and various excited states of triplet and singlet VCH have been calculated using ab initio multiple reference configuration interaction (MRCI) methods. The ground state is calculated to be a 3Δ state arising predominantly from the single electron configuration ··8σ2 3π4 9σ1 1δ1 with a calculated V–C bond length of 1.7061 Å and a V–C stretching frequency of 837 cm−1, which are in excellent agreement with experiment. The first excited state is the corresponding isoconfigurational low spin state, 1Δ, which lies 4670 cm−1 above the ground state. Higher excited triplet states are found to correlate well with experimentally known states.