Electronic states of the C6H5CN+ ion studied using multiconfiguration wave functions

Abstract

Electronic states of the C6H5CN+ ion have been studied within C2v symmetry using the complete active space self-consistent field (CASSCF) and multiconfiguration second-order perturbation theory (CASPT2) methods in conjunction with an atomic natural orbital basis set. Adiabatic excitation energies (T 0), vertical excitation energies (T v), and relative energies () at the ground-state geometry of the C6H5CN molecule were calculated for eight electronic states of the C6H5CN+ ion. The CASPT2//CASSCF T 0 and CASPT2 T v and calculations all indicate that the 1 2B1, 1 2A2, 2 2B1, 1 2B2, 1 2A1, 2 2A1, 2 2B2, and 3 2B1 states are the eight lowest-lying states of C6H5CN+. In conjunction with the MS-CASPT2 T 0 and oscillator strength f calculations, we assigned the X, A, B, C, D, E, F, and G states of the C6H5CN+ ion to 1 2B1, 1 2A2, 1 2B2, 2 2B1, 1 2A1, 2 2A1, 2 2B2, and 3 2B1, respectively.