Dissociative recombination without curve crossing: study of HeH+

We present a new theory for calculating dissociative recombination (and dissociative attachment) cross sections applicable for systems with or without curve crossings. The theory uses the R-matrix method to build up N+1 electron 'curves' in an inner region which can be coupled in a full non-adiabatic treatment. We report the first ab initio determination of the low-energy dissociative recombination cross section for 4 HeH + . The cross section is found to be in good agreement with measurements, now disputed, made in a merged beam experiment.