The Molecular Aharonov-Bohm effect Redux

TL;DR

This paper introduces a solvable molecular collision model demonstrating Aharonov-Bohm-like topological effects in molecular scattering, challenging previous notions about the effect's dependence on the adiabatic limit.

Contribution

It presents a new model that predicts AB-like scattering without relying on the Born-Oppenheimer approximation, providing exact solutions and topological insights into molecular conical intersections.

Findings

Evidence of topological phase dislocation lines independent of collision energy.

Wilson loop phase integral equals -1 for odd and +1 for even number of conical intersections.

Contrasts with previous studies suggesting the MAB effect only survives in the adiabatic limit.

Abstract

A solvable molecular collision model that predicts Aharonov-Bohm (AB) like scattering in the adiabatic approximation is introduced. For it, we propagate coupled channel wave packets without resorting to a Born-Oppenheimer (BO) approximation. In those, exact, solutions we find evidence of topological phase dislocation lines that are independent of the collision energy and provide definitive signatures of AB-like scattering. The results of these simulations contrast with the conclusions of a recent study that suggests survival of the molecular Aharonov-Bohm (MAB) effect only in the adiabatic limit in which the nuclear reduced mass $\mu \rightarrow \infty$. We discuss generalizations of this model and consider possible screening of the Mead-Truhlar vector potential by the presence of multiple conical intersections (CI). We demonstrate that the Wilson loop phase integral has the value $-1$ if it encloses an odd-number of CI's, and takes the value $+1$ for an even number. Within the scope of this model, we investigate the ultra-cold limit of scattering solutions in the presence of a conical intersection and comment on the relevance of Wigner threshold behavior for s-wave scattering.