Ionic reactions in He nanodroplets: the [LiHHe] + complex and its possible energy pathways into products from ab initio calculations.

Ab initio calculations at the multiconfiguration self-consistent field level followed by a multireference configuration interaction were carried ou t along the two possible collinear approaches of the [LiHHe](+) system, while a three-dimensional calculation of the structures of that complex with LiH+ k ept at its equilibrium geometry was also completed at the same level of accuracy. The interaction forces of the lowest two electronic states indicate possi ble reactive behavior, with the first excited potential-energy surface clearly showing a barrierless path to HeH+ product formation. The details of the rea ctive pathways and their possible bearing on reaction processes, which could occur at the low temperature of a He nanodroplet holding LiH+ as an impurity, are analyzed and discus