Continuum Skyrme Hartree-Fock-Bogoliubov theory with Green's function method for neutron-rich Ca, Ni, Zr, Sn isotopes

Abstract

The possible exotic nuclear properties in the neutron-rich Ca, Ni, Zr, and Sn isotopes are explored with the continuum Skyrme Hartree-Fock-Bogoliubov theory formulated with the Green's function method, in which the pairing correlation, the couplings with the continuum, and the blocking effects for the unpaired nucleon in odd-A nuclei are properly treated. In the ph channel, the SLy4 parameter set is taken for the Skyrme interaction, and in the pp channel, the DDDI is adopted for the pairing interaction. With those parameters, the available experimental two-neutron separation energies S2n and one-neutron separation energies Sn are well reproduced. Much shorter drip lines predicted by Sn are obtained compared with those by S2n. The systematic studies of the neutron pairing energies −Epair shown that values of the odd-A nuclei are much smaller in comparison with those of the neighboring even-even nuclei due to the absent contribution of pairing energy by the unpaired odd neutron. By investigating the single-particle structures, the rms radii and the density distributions, the possible halo structures in the neutron-rich Ca, Ni, and Sn isotopes are predicted, in which the sharp increases of rms radii with significant deviations from the traditional r ∝ A 1/3 rule and very diffuse spatial distributions in densities are observed. By analyzing the contributions of different partial waves to the total neutron density ρ lj (r)/ρ(r), the orbitals locating around the Fermi surface especially those with low angular momenta are found the main reason causing the extended nuclear density and large rms radii. Finally, the numbers of the neutrons N λ (N0) occupied above the Fermi surface λn (in the continuum) are discussed, the behaviors of which are basically consistent with those of pairing energy, supporting the key role of the pairing correlations in the halo phenomena.