Topology of conical/surface intersections among five low-lying electronic states of CO_2: Multireference configuration interaction calculations

摘要

Multi-reference configuration interaction with single and double excitation method has been utilized to calculate the potential energy surfaces of the five low-lying electronic states ~1A_1, ~1A _2, ~3A_2, ~1B_2, and ~3B_2 of carbon dioxide molecule. Topology of intersections among these five states has been fully analyzed and is associated with double-well potential energy structure for every electronic state. The analytical potential energy surfaces based on the reproducing kernel Hilbert space method have been utilized for illustrating topology of surface crossings. Double surface seam lines between ~1A_1 and ~3B_2 states have been found inside which the ~3B_2 state is always lower in potential energy than the ~1A_1 state, and thus it leads to an angle bias collision dynamics. Several conical/surface intersections among these five low-lying states have been found to enrich dissociation pathways, and predissociation can even prefer bent-geometry channels. Especially, the dissociation of O(~3P) + CO can take place through the intersection between ~3B_2 and ~1B_2 states, and the intersection between ~3A_2 and ~1B_2 states.