A theoretical description of multi-channel fragmentation of the Na3+ cluster-ion in collision with a He target

Fragmentation of the Na3+ cluster-ion in collision with He in the 100 eV (centre of mass) energy range is investigated theoretically. The dynamics study is split into two stages: the He–Na3+ encounter itself and the post-collisional motion of the Na3+ cluster-ion. The first stage is treated semiclassically and involves a `frozen cluster approximationʹ. The second stage is treated by a trajectory surface hopping procedure. The two stages make use of diabatic and adiabatic representations, respectively and involve diatomics-in-molecules calculations. For the He–Na3+ system, an adaptation of the DIM approach incorporating three-centre integrals is employed. Different fragmentation mechanisms are discussed and comparison with experiment is made.