Non-Hermitian topology in molecules: Prediction of fractional quantum number

TL;DR

This paper introduces a non-Hermitian topological model for molecules, predicting Weyl points and fractional quantum numbers caused by finite lifetime effects, revealing novel topological phenomena in molecular systems.

Contribution

It presents a simple toy model showing how non-Hermitian effects induce Weyl points and Fermi arcs in molecules, linking non-Hermitian topology to molecular Jahn-Teller phenomena.

Findings

Weyl points are predicted in molecules due to non-Hermitian effects.

Fermi arcs connect Weyl points, with length depending on non-Hermitian strength.

Fractional quantum numbers emerge from the non-Hermitian topology.

Abstract

We give a simple toy model to study a famous Jahn-Teller type molecule. Finite lifetime due to non-adiabatic coupling and finite temperature effect results in the effective Hamiltonian to be non-Hermitian. This effect pulls a conical intersection into a pair of connected Weyl points, bridged by a Fermi arc. The length of the Fermi arc depends on the strength of non-hermicity. This is a unique feature of non-Hermitian topology with no Hermitian analogue. We predict the existence of Weyl points in molecules which cause anomalous Jahn-Teller effects and fractional quantum number.