Radiative association rates and structure of resonances for Li and Li+ colliding with H and H+

The radiative association rates are computed, using an entirely ab initio approach, for Li and Li+ atoms interacting with H and H+. The accurate potential energy curves obtained for such systems in an earlier study (Gianturco et al. 1996) are employed, and the corresponding transition moments are also used to evaluate the cross sections. The final rates are shown generally to decrease with temperature in the range from 50 to 5000 K, in close agreement with the behavior of recent calculations (Dalgarno et al. 1996). At low collision energies, all the systems considered show interesting resonant structures that can be associated to specific final states of the bound products of the reactions. The importance of these rates of formation in the lithium chemistry of the early universe is also briefly discussed.