First Quantum Study of the Rotational Excitation of HCN by Para-H₂O: Convergence of Quantum Results, Influence of the Potential Energy Surface, and Approximate Rate Coefficients of Interest for Cometary Atmospheres
The rotational excitation of HCN by H2O, the main perturber in cometary atmospheres, is investigated using quantum methodologies. We provide approximate rotational de-excitation rate coefficients among the first levels of HCN perturbed by thermalized para-water in the temperature range T = 5K to T = 150K. Because of the novelty of the system for quantum rotational excitation, the current study includes a detailed appreciation of the parameters involved in the convergence of the cross-sections and of rate coefficients calculations. A compromise on the convergence of the rate coefficients with respect to the rotational basis set is taken because of the computing time cost. Moreover, because of the cost also involved in calculating the 5D potential energy surfaces necessary for the current dynamical calculations, several potential energy surfaces of increased quality are tested and it is shown that, within the current approximations on the collisional calculations, average quality potential energy surfaces are sufficient for cometary applications.
M. Dubernet and E. Quintas-Sánchez, "First Quantum Study of the Rotational Excitation of HCN by Para-H₂O: Convergence of Quantum Results, Influence of the Potential Energy Surface, and Approximate Rate Coefficients of Interest for Cometary Atmospheres," Molecular Astrophysics, vol. 16, Elsevier, Sep 2019.
The definitive version is available at https://doi.org/10.1016/j.molap.2019.100046
Keywords and Phrases
Comets; Quantum rate coefficients; Rotational excitation
International Standard Serial Number (ISSN)
Article - Journal
© 2019 Elsevier, All rights reserved.
01 Sep 2019