Multireference configuration interaction calculations of the low-lying electronic states of ClO2

Abstract

Using extensive internally contracted multireference configuration interaction wave functions and large basis sets, near-equilibrium potential energy functions for the first four doublet electronic states (X 2B1, 2B2, 2A1, and A 2A2 ) of OClO and the X 2A″ electronic state of ClOO have been calculated. Electric dipole moment functions have also been computed for the ground states of both isomers. Spectroscopic constants derived for the X and A states of OClO, as well as for the X state of ClOO, are compared to the available experimental data, and predictions for the other states are made. In agreement with previous assumptions about the photodissociation of OClO, strong interactions between the first three excited electronic states in the Franck–Condon region of the A←X transition are indicated from cuts of the potential energy surfaces. In particular, the experimentally observed predissociation of the A 2A2 state is proposed from this work to proceed initially by an interaction with the close-lying 2A1 state. Additionally, the calculated asymmetric stretch potential for the A 2A2 state of OClO does not show evidence of a double minimum as has been previously proposed.