Periodic-orbit bifurcations as the origin of nuclear deformations

Semiclassical analysis of shell structures in realistic nuclear potentials are presented using periodic-orbit theory. We adopted r^alpha potential model and examined classical-quantum correspondence using Fourier transformation technique. Spin-orbit coupling is also taken into account in the model Hamiltonian. Gross shell structure for a certain combination of surface diffuseness and spin-orbit parameters are investigated and its relation to pseudospin symmetry is discussed. Analysis of superdeformed shell structure in realistic model is also presented.