Quantum mechanical study of the high-temperature H+ + HD -> D+ + H-2 reaction for the primordial universe chemistry

We use the time-independent quantum-mechanical formulation of reactive collisions in order to investigate the state-to-state H+ + HD -> D+ + H-2 chemical reaction. We compute cross-sections for collision energies up to 1.8eV and rate coefficients for temperatures up to 10000K. We consider HD in the lowest vibrational level v= 0 and rotational levels j= 0-6, and H-2 in vibrational levels v `= 0-3 and rotational levels j `= 0-9. For temperatures below 4000K, the rate coefficients strongly vary with the initial rotational level j, depending on whether the reaction is endothermic (j <= 2) or exothermic (j >= 3). The reaction is also found less and less probable as the final vibrational quantum number v ` increases. Our results illustrate the importance of studying state-to-state reactions, in the context of the chemistry of the primordial universe.