Collisional ‘heating’ of molecular rotations by positron impact: a computational analysis of the quantum dynamics

Abstract

Low-energy collisional excitation of rotational levels by impact with slow positron beams is considered by carrying out a space-frame (SF) dynamical calculation at energies well below the positronium formation threshold. The close-coupled quantum equations are solved exactly, using a recently developed modified variable phase approximation (MVPA) and the interaction forces include static interaction exactly and a local, DFT modelling of correlation–polarisation effects. The results are employed to obtain heating and quenching efficiency coefficients for a series of linear molecules in the gas phase and at low collision energies.