MICROSCOPIC ASPECTS OF NUCLEAR-DEFORMATION

The self-consistent approach based on the Skyrme Hartree-Fock+BCS mode l is used to analyze the microscopic origin of nuclear equilibrium def ormations. Neutron-proton, neutron-neutron and proton-proton multipole interaction energies are analyzed and their role in the onset of quad rupole deformation is discussed. It is concluded that nuclear deformat ion results from a subtle interplay between the deformation-driving ne utron-proton part of the energy (varying smoothly with the shell filli ng) and the symmetry-restoring monopole part of the total energy (resp onsible for shell effects). Shell fluctuations of the monopole part of the total energy are discussed in terms of the Nilsson model. The int erplay of normal-parity and unique-parity orbitals in controlling the systematic behavior of strongly deformed intrinsic configurations is a nalyzed within the shell-correction approach.