Breakdown of energy transfer gap laws revealed by full-dimensional quantum scattering between HF molecules

Dongzheng Yang,Jing Huang,Daiqian Xie,Xixi Hu,Hua Guo

doi:10.1038/s41467-019-12691-8

Dongzheng Yang, Jing Huang + Show 3 more

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https://doi.org/10.1038/s41467-019-12691-8

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Journal: Nature Communications	Publication Date: Oct 11, 2019
Citations: 17	License type: open-access

Affiliation: Nanjing University, University of New Mexico

Abstract

Inelastic collisions involving molecular species are key to energy transfer in gaseous environments. They are commonly governed by an energy gap law, which dictates that transitions are dominated by those between initial and final states with roughly the same ro-vibrational energy. Transitions involving rotational inelasticity are often further constrained by the rotational angular momentum. Here, we demonstrate using full-dimensional quantum scattering on an ab initio based global potential energy surface (PES) that HF–HF inelastic collisions do not obey the energy and angular momentum gap laws. Detailed analyses attribute the failure of gap laws to the exceedingly strong intermolecular interaction. On the other hand, vibrational state-resolved rate coefficients are in good agreement with existing experimental results, validating the accuracy of the PES. These new and surprising results are expected to extend our understanding of energy transfer and provide a quantitative basis for numerical simulations of hydrogen fluoride chemical lasers.

Highlights

Inelastic collisions involving molecular species are key to energy transfer in gaseous environments
A notation labeled by four quantum numbers (v1, j1; v2, j2) is used to describe a combined molecular state (CMS), which is the combination of ro-vibrational states of two diatoms before or after a collision[18]
We report the converged full-dimensional quantum mechanical cross-sections for the hydrogen fluoride (HF)–HF inelastic scattering on a newly developed global potential energy surface (PES) based on high-level ab initio calculations

Summary

Introduction

Inelastic collisions involving molecular species are key to energy transfer in gaseous environments They are commonly governed by an energy gap law, which dictates that transitions are dominated by those between initial and final states with roughly the same ro-vibrational energy. Vibrational state-resolved rate coefficients are in good agreement with existing experimental results, validating the accuracy of the PES These new and surprising results are expected to extend our understanding of energy transfer and provide a quantitative basis for numerical simulations of hydrogen fluoride chemical lasers. Collision-induced energy transfer is a fundamentally important process in many gas-phase chemical environments, such as combustion[1], atmospheric chemistry[2], astrochemistry[3], and chemical laser engineering[4]. Dynamical calculations for HF self-relaxation have only been performed in 1970s30–33, employing the quasi-classical trajectory (QCT)

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