Classical trajectory calculations of collision energy dependence of Penning ionization cross-sections for N₂ and CO by He*2 ³S; Optimization of anisotropic model potentials

Anisotropic potential energy surfaces were optimized for classical trajectory calculations in order to reproduce collision energy dependence of partial Penning ionization cross-sections for N₂ and CO molecules with a He^*(2³S) atom. Ab initio model potentials using a Li(2²S) atom in place of a He^*(2 ³S) atom based on the similarity of valence electronic configurations were found to be successfully corrected by addition of negative terms including an exponential function combined with Legendre expansions. Optimized sets of parameters demonstrate that the most important correction terms are related to attractive interactions due to electron transfer from He^*(Li) to unoccupied molecular orbitals.