Non-adiabatic coupling as friction in the formation of H3+: A classical mechanical study

TL;DR

This study models non-adiabatic couplings as frictional forces in classical mechanics to explain the formation of H3+ and DH2+ during molecular collisions, going beyond traditional approximations.

Contribution

It introduces a novel classical approach treating non-adiabatic couplings as friction, providing new insights into molecular collision dynamics and ion formation.

Findings

NACTs can be modeled as frictional forces affecting molecular collisions

Collision dynamics show trapping and formation of DH2+

Classical equations of motion predict slowed collision processes

Abstract

By going beyond the Born-Oppenheimer approximation and treating the non-adiabatic coupling terms (NACTs) as equivalent to a frictional force in a molecular system, the classical equations of motion are solved for a test case of H3+. Using an ab initio potential energy surface for the ground electronic state and its NACTs with the first excited state of H3+, it is shown that (D+, H2) collisions are slowed enough to result in trapping and formation of a stable DH2+.