Theoretical calculations of C2v excited states of

The 2B2, 2A2 and 2B1 ionic excited states of sulfur dioxide were studied by quantum calculations with the density functional theory (B3LYP functional) and the coupled cluster singles and doubles with perturbative triples [CCSD(T)] methods. The optimized structure of the 2B2 state was of a transition state correlating to an equilibrium geometry of the Cs point group, contrary to previous studies. The 2B1 state has two equilibrium structures of a bent and a cyclic geometry. By the computation of Franck–Condon factors, the photoelectron spectrum of the 2A2 state was simulated and was found to be in agreement with the experiment, but with different assignments.