The Berry phase in a T(X) τ₂Jahn-Teller system, with a note on tunnelling

Abstract

The phase of the wavefunction on the lowest adiabatic potential energy surface of a T(X) τ2 Jahn-Teller system is studied, and a mapping for the lowest energy states is proposed. Methods of calculating the tunnelling splitting at strong coupling are discussed, and tested by application to a soluble one-dimensional equation.