Nuclear Low-lying Spectrum And Shape Transition Within Covariant Density Functional Based Collective Hamiltonian

Nuclear spectroscopic properties especially the low-energy excited states of collective nature reflecting the wealth of nuclear structure, including the evolution of nuclear shape, shape coexistence and evolution of collectivity and shell structure. Recently we have developed the five dimensional collective Hamiltonian (5DCH) based on the covariant density functional theory, which achieves great success in describing the nuclear low-lying spectra and quantum phase transition aspects. In this paper, we use the5DCH model to carry out the following investigations:1) Low-lying excited states and evolution of collectivity in near spherical nuclei. Using the PC-PK1density functional to study the evolution of low-energy excited states in Sn isotopes, the model reproduces well the excitation energy of2+state and B(E2;00+â†'21+), in particular, the enhanced E2transition strength in neutron-deficient Sn (N<66) isotopes. Furthermore, we find that other energy functionals, e.g. PC-F1and DD-PC1, can give similar conclusion, we also use5DCH model to study the potential energy surfaces and excited-states of neutron-rich64-68Ni isotopes.2) Shape transition and systematics of low-lying spectrum in nuclei at N≈90. We have calculated the potential energy surfaces, low-lying spectrum, and energy staggering of y band in nuclei at N≈90using5DCH model and compared with the experimental values. Theoretical model reproduces well the shape evolution of the nuclear transition, spectral properties and the systematics of low-lying spectrum.