Berry's geometric quantum phase and the T₁⊗ (ε_g⊕ τ_2g) Jahn-Teller effect

Abstract

The ground-state wavefunctions of the linear octahedral Jahn-Teller system T1 ⊗(εg ⊕ τ2g) are shown to exhibit a Berry phase for certain closed circuits in phonon coordinate space. This is shown to result from the coupling between the electronic and phonon parts of the system and from the requirement that the total wavefunction be single-valued. The associated Berry vector potential is also calculated and is interpreted in terms of a flux line.