Towards a shell model description of the low-energy structure of deformed nuclei I. Even-even systems

A microscopic shell model theory for the low-lying collective states of heavy deformed nuclei is described. Basis selection is guided by the Bohr-Mottelson-Nilsson picture of collective motion in nuclei. The necessary further truncation is achieved by exploiting an SU(3) symmetry inherent to the structure of the normal parity states and by restricting abnormal parity configurations to states with low seniority. An effective interaction comprised of operators which form an integrity basis for the SU(3)..-->..R(3) algebra is shown to be sufficient to reproduce almost exactly, within a single leading irreducible representation of SU(3), the ground and gamma band rotational structure of eight rare earth (/sup 160/Dy, /sup 162/Dy, /sup 164/Dy, /sup 164/Er, /sup 166/Er, /sup 168/Er, /sup 166/Yb, /sup 168/Yb) and four actinide (/sup 232/Th, /sup 234/U, /sup 236/U, /sup 238/U) nuclei. The concomitant interband and intraband E2 strengths are also shown to be accurately reproduced. Extensions of the theory and necessary further theoretical investigations are reviewed.

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