Ab initio spectroscopy of D2H+ near dissociation

Extensive calculations for the vibrational band origins of D2H+ up to dissociation are presented. Due to the high density of vibrational states near dissociation, huge basis sets needed to be used as well as massively parallel computers. We have found 1209 A1 and 1078 B1 bound states, some of which display long-range features, which are analysed in detail. The calculations were performed within the Born–Oppenheimer approximation and non-adiabatic corrections to it are evaluated. However, the main source of error for the states near dissociation arises from the Potential Energy Surface at high energies.