Results

Figure 1 shows the PNP results for the complete chain of the calcium isotopes (from the proton drip to the neutron drip line), calculated with the SLy4 Skyrme functional and mixed delta pairing [1]. Comparison is also made with the LN and PLN results. One can conclude that the PLN approximation works best for open-shell nuclei, where the total energy differences between various variants of calculations are less than 250keV. For closed-shell nuclei [5], however, the energy differences increase to more than 1MeV. In such cases, one can improve the PLN results by applying the projection to the LN solutions obtained for the neighboring nuclei [6], as illustrated in the top panel of Fig. 1.

Figure 1: The LN and PLN (projection after variation) and PNP HFB (projection before variation) results obtained for the SLy4 force and mixed delta pairing. Arrows in the top panel indicate projection results from the neighboring nuclei.

In summary, the Skyrme HFBTHO PNP framework has been implemented and tested. The particle-number corrections maximize for magic nuclei where the static pairing breaks down. It is to be noted that conceptual questions related to the notion of symmetry restoration in DFT still remain; those will be discussed in the following work [7].