DISSOCIATIVE RECOMBINATION WITHOUT A CURVE CROSSING

Ab initio calculations show that a curve crossing is not always needed for a high dissociative-recombination cross section. For HeH+, in which no neutral states cross the ion potential curve, dissociative recombination is driven by the nuclear kinetic-energy operator on adiabatic potential curves. The kinetic-energy derivative operator allows for capture into repulsive curves that are outside of the classical turning points for the nuclear motion. The dominant dissociative route is the C2SIGMA+ state leading to H(n = 2) atoms. An analogous mechanism is proposed for the dissociative recombination of H-3+.