State-resolved rotational cross sections and thermal rate coefficients for ortho-/para-H2+HD at low temperatures and HD+HD elastic scattering

TL;DR

This paper presents quantum mechanical calculations of rotational cross sections and thermal rate coefficients for ortho-/para-H2+HD collisions at low temperatures, highlighting resonances and their impact on astrophysical gas cooling.

Contribution

It provides new quantum mechanical data on low-temperature rotational cross sections and rate coefficients for H2+HD collisions, including resonance effects, relevant for astrophysics.

Findings

Sharp resonances significantly affect low-temperature rate coefficients.

Calculated elastic HD+HD cross sections agree with previous theories and experiments.

Resonance contributions are crucial below 100 K.

Abstract

Results for quantum mechanical calculations of the integral cross sections and corresponding thermal rate coefficients for para-/ortho-H2+HD collisions are presented. Because of significant astrophysical interest in regard to the cooling of primodial gas the low temperature limit of para-/ortho-H2+HD is investigated. Sharp resonances in the rotational state-resolved cross sections have been calculated at low energies. These resonances are important and significantly contribute to the corresponding rotational state-resolved thermal rate coefficients, particularly at low temperatures, that is less than $T \sim 100$K. Additionally in this work, the cross sections for the elastic HD+HD collision have also been calculated. We obtained quite satisfactory agreement with the results of other theoretical works and experiments.