Total angular momentum representation for atom-molecule collisions in electric fields

TL;DR

This paper introduces a total angular momentum representation in the body-fixed frame for atom-molecule collisions under electric fields, significantly improving computational efficiency for low-temperature scattering calculations.

Contribution

It presents a novel, efficient method using total angular momentum in the body-fixed frame for modeling atom-molecule collisions in electric fields, enabling more feasible quantum scattering calculations.

Findings

Rapid convergence of cross sections with basis set size

5-100 fold increase in computational efficiency

Potential to enable extensive quantum scattering studies

Abstract

It is shown that the atom-molecule collision problem in the presence of an external electric field can be solved using the total angular momentum representation in the body-fixed coordinated frame, leading to a computationally efficient method for ab initio modeling of low-temperature scattering phenomena. Our calculations demonstrate rapid convergence of the cross sections for vibrational and Stark relaxation in He-CaD collisions with the number of total angular momentum states in the basis set, leading to a 5-100 fold increase in computational efficiency over the previously used methods based on the fully uncoupled space-fixed representation. These results open up the possibility of carrying out numerically converged quantum scattering calculations on a wide array of atom-molecule collisions and chemical reactions in the presence of electric fields.