Conical intersections induced by the Renner effect in polyatomic molecules

TL;DR

This paper reveals that the Renner effect in polyatomic molecules with more than three nuclei inherently causes satellite conical intersections, influencing electronic energy flow, supported by ab initio results on C2H2+.

Contribution

It introduces a topological phase-based framework linking the Renner effect to satellite conical intersections in polyatomic molecules with more than three nuclei.

Findings

Satellite conical intersections are necessarily induced by the Renner effect.

Non-adiabatic coupling terms are on average half an integer at these intersections.

Ab initio calculations on C2H2+ support the theoretical predictions.

Abstract

Characterizing and localizing electronic energy degeneracies is important for describ-ing and controlling electronic energy flow in molecules. We show, using topological phase considerations that the Renner effect in polyatomic molecules with more than 3 nuclei is necessarily accompanied by 'satellite' conical intersections. In these intersections the non-adiabatic coupling term is on the average half an integer. We present ab-inito results on the tetra-atomic radical cation C2H2+ to demonstrate the theory