The role of the Berry Phase in Dynamical Jahn-Teller Systems

TL;DR

This paper explores how the Berry phase influences the topology and degeneracy of dynamical Jahn-Teller systems, with implications for fullerene ions and classification of these systems based on their Berry phase properties.

Contribution

It provides a detailed analysis linking topological properties of Jahn-Teller potential minima to the presence or absence of the Berry phase, including a classification scheme for spherical Jahn-Teller systems.

Findings

Berry phase depends on the topology of potential minima

Classification of spherical Jahn-Teller systems by Berry phase

Absence of Berry phase does not always mean nondegenerate ground state

Abstract

The presence/absence of a Berry phase depends on the topology of the manifold of dynamical Jahn-Teller potential minima. We describe in detail the relation between these topological properties and the way the lowest two adiabatic potential surfaces get locally degenerate. We illustrate our arguments through spherical generalizations of the linear T x h and H x h cases, relevant for the physics of fullerene ions. Our analysis allows us to classify all the spherical Jahn-Teller systems with respect to the Berry phase. Its absence can, but does not necessarily, lead to a nondegenerate ground state.