Description of Alternating Parity Bands in Deformed Even-Even Nuclei in the Symplectic Extension of the Interacting Vector Boson Model

We revise the classification of even and odd parity states in the symplectic multiplets of the Sp(12 ,R ) dynamical symmetry of the Interacting Boson Model /IVBM/. This new classification is tested in an application of the model for the description of different parity low laying bands. We analyze the behavior of the first excited 0 − band in respect to the yrast and some of the other excited 0 + bands. Their energies are well reproduced by means of a simple generalization of the rigid rotor expression for them. The relations between the phenomenological parameters of the model Hamiltonian and the generalized rotor are obtained. The dependence of the model parameters on the collective structure of the band head configurations is explored and analyzed.