Title

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

Abstract

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.

Department(s)

Chemistry

Keywords and Phrases

Comets; Quantum rate coefficients; Rotational excitation

International Standard Serial Number (ISSN)

2405-6758

Document Type

Article - Journal

Document Version

Citation

File Type

text

Language(s)

English

Rights

© 2019 Elsevier, All rights reserved.

Publication Date

01 Sep 2019

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