The gas-phase lithium chemistry in the early universe: elementary processes, interaction forces and quantum dynamics

In this work we review the efforts made in the last 10 years to understand the neutral and ionic chemistry of LiH. The relevance of most of the stu dies on this subject is due to the possible importance of the LiH molecules and relative ions in the primordial universe chemistry. Although it is still no t clear what could be the role of LiH in the early universe chemistry, since experimentally important data are indeed still missing and its relevance may b e limited by the small abundance of Li molecular species that is thought to exist at the recombination era, it is already important from a fundamental poin t of view to gather the various results obtained up to now since, in our opinion, they are already able to shed light on a large portion of the gas-phase c hemistry of LiH and of its positive ion. Most of the results that will be summarized here are theoretical and computational, intending to provide the prese nt state of our knowledge on the relevant potential energy surfaces and dynamical processes which ensue from their features. (C) 2003 Elsevier B.V. All rig hts reserved