Low-lying states in even Gd isotopes studied with five-dimensional collective Hamiltonian based on covariant density functional theory

Five-dimensional collective Hamiltonian based on the covariant density functional theory has been applied to study the low-lying states of even-even ^148-162Gd isotopes. The shape evolution from ¹⁴⁸Gd to ¹⁶²Gd is presented. The experimental energy spectra and intraband B(E2) transition probabilities for the ^148-162Gd isotopes are reproduced by the present calculations. The relative B(E2) ratios in present calculations are also compared with the available interacting boson model results and experimental data. It is found that the occupations of neutron 1 i_{13 / 2} orbital result in the well-deformed prolate shape, and are essential for Gd isotopes.