Quantum dynamics of CO-H$_2$ in full dimensionality

TL;DR

This paper presents highly accurate full-dimensional quantum calculations of CO vibrational quenching due to H$_2$ collisions, providing essential data for astrophysical models and demonstrating the largest such computations to date.

Contribution

It introduces the first comprehensive six-dimensional quantum scattering calculations for CO-H$_2$ rovibrational quenching, advancing computational methods in molecular collision studies.

Findings

Results agree with experimental data, confirming accuracy.

Largest full-dimensional quantum scattering calculations performed to date.

Provides essential rovibrational quenching data for astrophysical applications.

Abstract

Accurate rate coefficients for molecular vibrational transitions due to collisions with H$_2$, critical for interpreting infrared astronomical observations, are lacking for most molecules. Quantum calculations are the primary source of such data, but reliable values that consider all internal degrees of freedom of the collision complex have only been reported for H$_2$-H$_2$ due to the difficulty of the computations. Here we present essentially exact full-dimensional dynamics computations for rovibrational quenching of CO due to H$_2$ impact. Using a high-level six-dimensional potential surface, time-independent scattering calculations, within a full angular-momentum-coupling formulation, were performed for the deexcitation of vibrationally excited CO. Agreement with experimentally-determined results confirms the accuracy of the potential and scattering computations, representing the largest of such calculations performed to date. This investigation advances computational quantum dynamics studies representing initial steps toward obtaining CO-H$_2$ rovibrational quenching data needed for astrophysical modeling.