Effects of rotational degree of freedom on calculations of photoassociation of HeH+ systems

Abstract

The role of rotational degree of freedom in calculations of photoassociation (PA) and the accompanying phenomena, that is, multiphoton transitions and above-threshold dissociations (PA-ATDs), of HeH+ systems is investigated by comparing the numerical results of the one-dimensional (1D) and three-dimensional (3D) models in the framework of the time-dependent quantum wave packet method. It was found that the PA probability of the target state predicted by the 3D model is much smaller than that predicted by the 1D model. In addition, as the bound energies of interaction potential can be shifted by the inclusion of the rotational degree of freedom, the amplitude and frequency of optimized laser pulses obtained based on the 1D model should be changed to some extent to obtain maximal PA probability of the target state in realistic systems. The multiphoton transitions in the 3D case tend to be much easier to be excited. The variational behaviors of the PA-ATD probability vs the initial relative momentum of the two colliding particles, calculated in the 3D model using the optimized laser pulses obtained based on the 1D and 3D models, are found to be nearly coincident with each other, which implies that the continuum-continuum transitions from the initial wave packet tend to be the major dynamics in the PA-ATD process.