Quantum dynamics study of the D$^+$ + H$_2$ reaction at low temperature
Résumé
For chemistry networks describing the reactions for the early universe and especially for accurate models of the enrichment of deuterated molecules observed, we need to know in detail many state-to-state rate coefficients. For instance, Glover and Abel [1] modeled the chemistry of H2 and HD primordial gas using a chemical network consisting of 115 reactions between 16 species. Today most of the rate coefficients of interesting reactions are still unknown or with a poor accuracy. For example, the uncertainty about the rate coefficient for the reaction D+ + H2 --> HD + H+ directly affects model predictions for the HD abundance and thereby the cooling rate of the primordial gas. It is therefore of astrophysical importance to determine an accurate value of these rates, and helping to understand the cooling requires a complete set of the state-to-state rate coefficients as well as the total rate coefficient.We have thus studied the reaction with Time Independent Quantum Mechanical (TIQM) and Statistical Quantum Mechanical (SQM) methods and using the recent potential energy surface of Velilla et al. determined for H3+ [2]. The state to state cross sections at low collisional energies and rate coefficients at low temperature have been computed and are compared to the available experimental data [3,4]. The TIQM results are also compared with the SQM results for this low energy regime [5].[1] Glover S.C. O., Abel T., Mon. Not. R. Astron. Soc. , 2008, 388, 1627. [2] Velilla L. et al., J. Chem. Phys. A , 2008, 129, 084307.[3] Honvault P. and Scribano Y., J. Phys. Chem. A , 2013, in press. (DOI: 10.1021/jp3124549).[4] Gerlich D. and Schlemmer S., Planet. Space Sci. , 2002, 50, 1287.[5] Gonzalez Lezana T., Honvault P. and Scribano Y., submitted to J. Chem. Phys.