Inelastic Triatom-Atom Quantum Close-Coupling Dynamics in Full Dimensionality: all rovibrational mode quenching of water due to H impact on a six-dimensional potential energy surface

TL;DR

This paper presents a numerically exact six-dimensional quantum close-coupling calculation of water's rovibrational quenching due to hydrogen collisions, providing precise data for astrophysical models.

Contribution

It introduces the first full-dimensional 6D quantum close-coupling method for water-H collisions, improving accuracy over previous 4D approximations.

Findings

General agreement with previous 4D results but with notable differences.

First-time data for symmetric and asymmetric stretch mode quenching.

Provides accurate inelastic collision data for astrophysical applications.

Abstract

The rovibrational level populations, and subsequent emission in various astrophysical environments, is driven by inelastic collision processes. The available rovibrational rate coefficients for water have been calculated using a number of approximations. We present a numerically exact calculation for the rovibrational quenching for all water vibrational modes due to collisions with atomic hydrogen. The scattering theory implements a quantum close-coupling (CC) method on a high level ab initio six-dimensional (6D) potential energy surface (PES). Total rovibrational quenching cross sections for excited bending levels were compared with earlier results on a 4D PES with the rigid-bender close-coupling (RBCC) approximation. General agreement between 6D-CC and 4D-RBCC calculations are found, but differences are evident including the energy and amplitude of low-energy orbiting resonances. Quenching cross sections from the symmetric and asymmetric stretch modes are provided for the first time. The current 6D-CC calculation provides accurate inelastic data needed for astrophysical modeling.