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 map 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+ structures were found. Both can easily isomerize along the bending coordinate to the linear centrosymmetric global minimum of the electronic ground state. This finding is in accord with the interpretation of the low energy collision 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 ground 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)(+) with 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 Elsevier Science B.V. All rights reserved.