On the potential energy functions of the electronic states of CO2+

For the C+(P-2) + O-2((3)Sigma(g)(-))-->CO+(X(2)Sigma(+))+ O(P-3) reaction, combined diatomics-in-molecules and ab initio computations were used to ma p parts of its global potential energy function. In the entrance channel on the (II)-I-2 PEF's secondary minima in linear OOC+ and bent C-2v OCO+ stru ctures were found. Both can easily isomerize along the bending coordinate t o the linear centrosymmetric global minimum of the electronic ground state. This finding is in accord with the interpretation of the low energy collis ion experiments. The linear OOC+ minimum is embedded between the B(2)Sigma( u)(+) and C(2)Sigma(g)(+) states of CO2+. The avoided crossing regions, the crossings with the lowest quartet state and the conical intersections for the four lowest doublet states were located. The (XIIg)-I-2 electronic grou nd state is found to be vibronically coupled with the A(2)II(u), state, the A(2)II(u), state with the B(2)Sigma(u)(+) state, and the B(2)Sigma(u)(+) w ith the C(2)Sigma(g)(+) state. The excited doublet states cross with the B- 4(1) component of the (IIu)-I-4 state for small bending angles. The doublet X, A and C-states have secondary minima in bent structures. (C) 1999 Elsev ier Science B.V. All rights reserved.