H3+ near dissociation: theoretical progress

The observation of an infrared spectrum of the H3+ 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 H3+, 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.