Calculation of predissociation rates in O22+ by ab initio MRD-CI methods Original Research Article

The dissociation mechanisms of different metastable states in O22+ have been investigated theoretically. Spin–orbit coupling matrix elements have been determined using ab initio configuration interaction (CI) wave functions and employing both one- and two-electron terms of the Breit–Pauli Hamiltonian. Comparisons with data from earlier experimental studies [M. Lundqvist et al., J. Phys. B: At. Mol. Opt. Phys. 29 (1996) 499] have been made. Overall, the calculations support the interpretation that production of ionic fragments by predissociation of metastable states is governed by spin–orbit coupling to purely repulsive electronic states. One exception is the 1 1Πg state, for which it is probably necessary to take spin–spin coupling effects into consideration. For the B 3Σu− state a detailed comparison with experiments could be made. Good agreement between theoretical and experimental lifetimes were obtained after a uniform shift of 0.02 Å in equilibrium distance and about 0.1 eV in energy of the B 3Σu− potential curve.