SHELL-MODEL SCHEME FOR QUADRUPOLE PHENOMENA IN HEAVY DEFORMED-NUCLEI

The microscopic collective model, which extends the seminal work of Elliott on the SU(3) model for describing the structure of light deformed nuclei to include multiple 2h-omega shell-model excitations of the monopole (l = 0) and quadrupole (l = 2) type, is shown to be a logical extension of the pseudo SU(3) scheme for heavy deformed nuclei. The main advantage of this extended theory is that E2 transition strengths, intraband as well as interband, can be reproduced without introducing effective charges. Results for both Mg-24 and Er-168 are presented. The symmetry algebra of this extended theory is that of the symplectic group Sp(3,R) which contains SU(3) as a subgroup. It is therefore also called the symplectic model and in the case of the pseudo SU(3) extension, the pseudo-symplectic model. Basic premises of the theory are reviewed.