Effective Hamiltonian approach to doubly degenerate electronic states. I - Theory and applications to E ⊗ (b1 + b2) and related Jahn-Teller systems.

International audienceSeveral problems in vibronic spectroscopy are solved within the effective Hamiltonian formalism combined with Lie algebraic methods. We consider mainly vibronic interactions in orbital doublets for molecules with a principal symmetry axis of order n = 4k (or n even for Dnd symmetry groups). Effective Hamiltonian models for E ⊗ (b1 + b2), E ⊗ (bi + aj) and E ⊗ (bi + e) Jahn-Teller dynamical systems are discussed as well as some correlations with previous studies established