Fully ab initio dynamics of fine-structure-changing transitions in collisions of Mg(3s3p3P) with He

Cross sections for intramultiplet transitions among the Mg(3s3p 3Pj) states induced by collisions with He(1S) are calculated by a close-coupling treatment based on ab initio Mg(3s3p 3P)+He(1S) potential curves. The degeneracy averaged j to j' cross sections are compared with previous close-coupling calculations of Orlikowski and Alexander (1984) based on a model potential description of the relevant electrostatic potential curves. Differences in the two sets of calculations are seen in the relative magnitudes of the 2 to 0 and 1 to 0 cross sections at low energy and in the oscillatory structure in the energy dependence of the cross sections. The results are interpreted within a fully adiabatic description which gives insight into the mechanisms involved in fine-structure-changing transitions in collisions of 3P atoms with closed-shell atoms.