The Longuet-Higgins Phase and Charge Transport in Molecular Rings

TL;DR

This paper explores how the Longuet-Higgins phase influences charge transport in molecular rings, revealing divergent responses at conical crossings and contrasting behaviors away from crossings, with implications for quantum models at various temperatures.

Contribution

It demonstrates the impact of the Longuet-Higgins phase on charge transport and divergence phenomena in molecular rings, providing new insights into quantum response behaviors.

Findings

Diverging charge response at conical crossings where phase is π

Vanishing response when phase is 0 away from crossings

Behavior observed in quantum models at zero and finite temperatures

Abstract

The Longuet-Higgins-Berry's phase has remarkable consequences for charge transport in molecular rings. For generic (conical) crossing, where the phase is $\pi$, a vanishing cause can lead to a diverging response in the amount of charge transport. Away from level crossings, when the phase is 0, a vanishing cause leads to a vanishing response. The divergence of the response near crossing is related to, but distinct from, the divergence that occurs in the generalized susceptibility. We illustrate this behavior for quantum models of molecular rings driven by a running wave of small amplitude at zero and finite temperatures.