Vibronic state symmetry,selection rule and transition probabilities for a molecular rearrangement process. The butadiene-cyclobutene rearrangement

Permutation-inversion group theory is applied to the classification of vibronic states, selection rules, and transition probabilities for a molecular rearrangement process in which the nuclear configuration of the molecule changes substantially. The advantage of the permutation-inversion group in this respect is that it is independent of any particular nuclear configuration.