Journal of Physics A Mathematical and General
The Berry phase for a threefold degenerate state
Arnout Jozef Ceulemans, M. Szopa
Abstract
Different expressions for calculating the Berry phase of adiabatic processes are reviewed and their limitations are discussed. These expressions are then applied to the case of a circuit surrounding a triple degeneracy. It is shown that the most general formula for the Berry phase requires the use of the full SU(3) invariance group of a T state coupled to in + tau 1 + tau 2 modes. The T*( in + tau 2 ) Jahn-Teller problem appears as a special case with SO(3) symmetry.