Dynamics of the Li + Li2 Reaction: Coexistence of Statistical and Direct Attributes

By using the accurate DMBE III potential energy surface for Li 3, we have carried out a detailed dynamics study of the title reaction. Besides reporting on the effect of translational and vibrational excitation of the reactants, a comparison is also presented for two models for defining the collision complex. The results support the coexistence of two different types of reaction mechanisms. One, characterized by long-lived trajectories, dominates at low-energy regimes and vibrational excitation. The other, mostly associated with direct type trajectories, starts to play a more important role at still reasonably low collisional energies, depending on the vibrational state of the reactants. It is also shown that, for initial vibrational excitation of diatomic, short-lived collision complexes can be associated with extensive randomization of vibrational energy.