Diatomics-in-molecules study of the ground and excited states of H3− Original Research Article

A systematic diatomic-in-molecules procedure is applied to the H3− system to calculate the potential energy surfaces of the ground and low-lying excited states over the full range of geometric configurations. The approach provides the correct behavior of the calculated potentials. A conical intersection of the ground-state and first excited-state surfaces is found in the D3h configuration. A detachment mechanism in H− + H2 collisions related to nonadiabatic transitions between the ground and first excited states is proposed and discussed.