A full-dimensional quantum dynamical approach to the vibrational predissociation of Cl_2-He_2

摘要

A full-dimensional,fully coupled wave packet method is proposed and applied to investigate the vibrational predissociation dynamics of the Cl_2(B,v')-He_2 complex.Simulations are carried out for the resonance states associated with the v' = 10-13 initial vibrational excitations of Cl_2,and the results are compared with the available experimental data.A good agreement with experiment is achieved for the resonance lifetimes(typically within experimental error)and the C1_2 fragment rotational distributions.The mechanism of dissociation of the two He atoms is found to be dominantly sequential,through the DELTA v' = -2 channel.The probabilities obtained for the DELTA v' = -1 dissociation channel are,however,overestimated due to the use of absorbing boundary conditions combined with finite grid effects.It is suggested that a mechanism of energy redistribution through the couplings between the van der Waals modes of the two weak bonds takes place in the DELTA v' = - 1 dissociation.This mechanism is consistent with the resonance lifetimes and C1_2 rotational distributions predicted.The favorable comparison with most of the experimental data supports the reliability of the potential used to model Cl_2(B,v ')-He_2,at least in the present range of v' levels.