Computational study on the O- and Cl-loss dissociations of ClOO

To study the O- and Cl-loss dissociations of the ClOO radical, we calculate, under Cs or C∞v symmetry, the O- and Cl-loss dissociation potential energy curves (PECs) from ten lower-lying states of ClOO at the multiconfigurational second-order perturbation theory (CASPT2) level. To further consider the nonadiabatic process, minimum-energy crossing point (MECP) between potential energy surfaces is optimized at the complete active space self-consistent-field (CASSCF) level. Since the spin-orbital coupling at located 22Π/14Σ+ MECP is calculated being zero, the nonadiabatic process in ClOO dissociations involved in this MECP are forbidden. Based on these results, we predict the O- and Cl-loss dissociation mechanisms of ClOO are direct since the excited states are unbounded. Moreover, we propose a new isomerization mechanism between OClO and ClOO, that is, OClO (X∼2B1) →OClO (A∼2A2) →ClOO (22A″) →ClOO (X∼2A″), in which less nonadiabatic processes are involved.