Ground state properties of Zn, Ge, and Se isotopic chains in covariant density functional theory

Abstract

A systematic investigation of the ground state deformation, the physical properties (two-neutron separation energy and neutron, proton, and charge radii), and the possibility of nuclear shape coexistence in Zn, Ge, and Se isotopes was performed using the relativistic Hartree-Bogoliubov formalism using density-dependent zero- and finite-range $NN$ interactions. Shape coexistence does not show up clearly in Zn isotopes. However, it is clear in most of the Ge and Se isotopes; the two coexistence minima are axial and triaxial in the case of Ge, while both are axial in the case of Se. Along all these chains one can see the existence of several transition points, where the ground state shape suddenly changes. This sudden change affects the evolution of the physical properties. The density of states near the Fermi level is a key factor in determining the ground state minima. Both point-coupling and meson-exchange models give similar results with few exceptions. A very good agreement is found with the available experimental data. The SU(3) proxy provides a reasonable prediction of the deformation value in the middle of the isotopic chain.