Nuclear landscape in a mapped collective Hamiltonian from covariant density functional theory

The nuclear landscape is investigated within the triaxial relativistic Hartree-Bogoliubov theory with the PC-PK1 density functional, and the beyond-mean-field dynamical correlation energies are taken into account by a microscopically mapped five-dimensional collective Hamiltonian without additional free parameters. The effects of triaxial deformation and dynamical correlations on the nuclear landscape are analyzed. The present results provide a better description of the experimental binding energies of even-even nuclei, in particular for medium and heavy mass regions, in comparison with previous global calculations with the state-of-the-art covariant density functionals DD-PC1 and TMA. The inclusion of the dynamical correlation energies plays an important role in the PC-PK1 results. It is emphasized that the nuclear landscape is considerably extended by the PC-PK1 functional in comparison with the previous results obtained with the covariant density functionals DD-PC1 and TMA, which may be due to the different isovector properties in the density functionals.

Figure 1

The bound even-even nuclei obtained in the triaxial RHB calculations using PC-PK1 (a) without and (b) with the dynamical correlation energies. The differences between the experimental binding energies [1] and the calculated ones are denoted by colors. The two-proton and two-neutron drip lines are also shown as solid lines in comparison with the ones obtained in the previous works: the spherical RCHB calculations with PC-PK1 [16], the axial RHB calculations with DD-PC1 [44], and the axial RMF plus BCS calculations with TMA [7]. The inset shows the root-mean-square deviations of binding energies ${\sigma }_B$ in different mass regions for the triaxial RHB results with PC-PK1, in comparison with those for the axial RHB results with DD-PC1 [44], the RMF plus BCS results with TMA [7], and the nonrelativistic triaxial HFB results with D1S [20]. The dynamical correlation energies are included in the PC-PK1 and D1S results.

Figure 2

Dynamical correlation energies calculated with the 5DCH based on the triaxial RHB calculations with PC-PK1.

Figure 3

Quadrupole deformations $\beta$ obtained in the present triaxial RHB calculations with PC-PK1. Triaxially deformed nuclei are denoted by black boxes.