A variational groundstate for the dynamic Jahn-Teller effect

Abstract

A set of variation states is constructed for a defect with degenerate states of E symmetry interacting with the modes of vibration of a cubic crystal. A projection operator is used to ensure that the states have the symmetry corresponding to the hamiltonian of the system. The energies of the ground and some excited states are derived together with the reduction factors for perturbations. Comparison shows that the cluster model cannot consistently give the values of these quantities except in the limit of strong interactions.