Classical trajectory studies of alkali atom-alkali dimer exchange reactions: Li+Li2

Abstract

The thermoneutral alkali atom-alkali dimer exchange reaction Li+Li2 → Li2 + Li has been studied on a LEPS surface, having a potential well of depth 8·30 kcal mole-1, using classical trajectory methods. The total reaction cross section, collision lifetime, differential reaction cross section and product energy disposal were calculated for seven initial collisional energies. Comparison with the results from statistical theories shows good agreement for energies up to a quarter of the well depth in the case of the energy disposal and for energies about equal to the well depth in the case of the angular scattering. At low collisional energies the reaction is found to proceed via a long-lived complex which is non-linear and non-rigid. About 50–60 per cent of the total available energy goes into internal motion of the product molecule and is partitioned almost equally between vibration and rotation at low energies with rotation being slightly favoured at higher energies. The calculated total reaction cross sections and energy disposal are similar to the results obtained from recent molecular beam studies of some alkali atom-alkali dimer exchange reactions.