DIATOMICS-IN-MOLECULES STUDY OF THE GROUND AND EXCITED-STATES OF H-3(-)

A systematic diatomic-in-molecules procedure is applied to the H-3(-) system to calculate the potential energy surfaces of the ground and lo w-lying excited states over the full range of geometric configurations . The approach provides the correct behavior of the calculated potenti als. A conical intersection of the ground-state and first excited-stat e surfaces is found in the D-3h configuration. A detachment mechanism in H- + H-2 collisions related to nonadiabatic transitions between the ground and first excited states is proposed and discussed. (C) 1997 P ublished by Elsevier Science B.V.