Theoretical investigation of the H + HD → D + H$_2$ chemical reaction for astrophysical applications: A state-to-state quasi-classical study

Duncan Bossion (1) , Steve Ndengue (2) , H. D. Meyer (3) , Fabien Gatti (4) , Yohann Scribano (1)

1 LUPM - Laboratoire Univers et Particules de Montpellier
2 University of Rwanda
3 PCI - Physikalisch-Chemisches Institut [Heidelberg]
4 ISMO - Institut des Sciences Moléculaires d'Orsay

We report a large set of state-to-state rate constants for the H + HD reactive collision, using Quasi-Classical Trajectory (QCT) simulations on the accurate H 3 global potential energy surface of Mielke et al. [J. Chem. Phys. 116, 4142 (2002)]. High relative collision energies (up to ≈56 000 K) and high rovibrational levels of HD (up to ≈50 000 K), relevant to various non thermal equilibrium astrophysical media, are considered. We have validated the accuracy of our QCT calculations with a new efficient adaptation of the Multi Configuration Time Dependent Hartree (MCTDH) method to compute the reaction probability of a specific reactive channel. Our study has revealed that the high temperature regime favors the production of H 2 in its highly rovibrationnally excited states, which can de-excite radiatively (cooling the gas) or collisionally (heating the gas). Those new state-to-state QCT reaction rate constants represent a significant improvement in our understanding of the possible mechanisms leading to the destruction of HD by its collision with a H atom.

Domaines: Chimie théorique et/ou physique; Autre

Duncan Bossion, Steve Ndengue, H. D. Meyer, Fabien Gatti, Yohann Scribano. Theoretical investigation of the H + HD → D + H$_2$ chemical reaction for astrophysical applications: A state-to-state quasi-classical study. Journal of Chemical Physics, 2020, 153 (8), pp.081102. ⟨10.1063/5.0017697⟩. ⟨hal-03064481⟩