Trajectory calculation of the effectiveness of reagent vibration in the H+2+He→HeH++H or He+H+H+ reactions

Total cross sections for the reaction of H+2(v′) with He were calculated for v′=0 to 5 over a range of total energies between 1 and 5 eV using classical mechanics. The potential surface used was an appropriate diatomics-in-molecules function adjusted to fit existing ab initio points. In agreement with experiment, reagent vibrational excitation is very effective in promoting formation of HeH+ or dissociation, a fact which we explain in terms of the increased range of the attractive forces when the H+2 bond is extended. This effect is not properly described by comparison collinear calculations.