H3+ near dissociation: theoretical progress

The observation of an infrared spectrum of the H +3 molecular ion at its dissociation limit by Carrington and co-workers has presented a tremendous challenge to theory. To compute this spectrum it is necessary to model accurately the global potential energy surface of H +3 , vibrationally excited states at dissociation, rotational excitation, lifetimes of rotationally excited `shape’ resonances, and infrared transition dipoles near dissociation. Progress in each of these aspects is reviewed and results are presented for highly excited vibrational levels using a new ab initio global potential. The use of massively parallel computers in solving aspects of the problem is discussed.