Multichannel Quantum Defect Theory for cold molecular collisions

TL;DR

This paper demonstrates that Multichannel Quantum Defect Theory (MQDT) can accurately and efficiently model low-energy atom-molecule collisions, significantly reducing computational costs for exploring energy and magnetic field effects.

Contribution

The paper introduces a method to use MQDT with a suitable reference potential and matching distance, enabling fast calculations of molecular scattering with minimal energy and field dependence.

Findings

MQDT provides quantitatively accurate results for low-energy scattering.

The method reduces computational cost from N^3 to N for multiple energies and fields.

It is promising for systems where full exploration is currently impractical.

Abstract

Multichannel Quantum Defect Theory (MQDT) is shown to be capable of producing quantitatively accurate results for low-energy atom-molecule scattering calculations. With a suitable choice of reference potential and short-range matching distance, it is possible to define a matrix that encapsulates the short-range collision dynamics and is only weakly dependent on energy and magnetic field. Once this has been produced, calculations at additional energies and fields can be performed at a computational cost that is proportional to the number of channels N and not to N^3. MQDT thus provides a promising method for carrying out low-energy molecular scattering calculations on systems where full exploration of the energy- and field-dependence is currently impractical.