The role of geometric phase in the formation of electronic coherences at conical intersections

TL;DR

This paper demonstrates that the geometric phase critically influences the formation and observation of electronic coherences at conical intersections, affecting their presence and magnitude depending on state symmetry and approach direction.

Contribution

It highlights the essential role of the geometric phase in accurately describing electronic coherences at conical intersections, a factor often neglected in previous models.

Findings

Electronic coherences are suppressed by the geometric phase for states of different symmetry.

For states of the same symmetry, electronic coherences can develop depending on the conical intersection topography.

The magnitude of coherences depends on the approach direction to the conical intersection.

Abstract

The direct observation of non-adiabatic dynamics at conical intersections is a long-standing goal of molecular physics. Novel time-resolved spectroscopies have been proposed which are sensitive to electronic coherences induced by the passage of an excited state wavepacket through a region of conical intersection. Here we demonstrate that inclusion of the geometric phase effect, and its manifestations, is essential for the correct description of the transient electronic coherences that may or may not develop. For electronic states of different symmetry, electronic coherences are suppressed by the geometric phase. Conversely, for states of the same symmetry, appreciable electronic coherences are possible, but their magnitude depends on both the topography of and direction of approach to the conical intersection. These general results have consequences for all studies of electronic coherences at conical intersections.