SHELL-STRUCTURE AND OCTUPOLE INSTABILITY IN FERMION SYSTEMS

Simulating the one-particle spectra of the infinite-well potential by a model, we study the symmetry and the shell-structure of octupole deformations as well as the possible occurrence of octupole (and quadrupole) instabilities. Among various types of octupole deformations investigated the Y32-type deformation is found to have a strong shell-structure as well as a very interesting symmetry which leads to the occurrence of highly-degenerate single-particle levels. One particle spectra of the octupole-coupled two-level model (with l and l + 3) are analytically studied in the limit of large angular-momentum, l.