Rotational properties of nuclei around 254 No investigated using a spectroscopic-quality Skyrme energy density functional

Abstract

Abstract. Background: Nuclei in the Z≈100 mass region represent the heaviest systems where detailed spectroscopic information is experimentally available. Although microscopic-macroscopic and self-consistent models have achieved great success in describing the data in this mass region, a fully satisfying precise theoretical description is still missing.

Purpose: By using fine-tuned parametrizations of the energy density functionals, the present work aims at an improved description of the single-particle properties and rotational bands in the nobelium region. Such locally optimized parametrizations may have better properties when extrapolating towards the superheavy region.

Methods: Skyrme Hartree-Fock-Bogolyubov and Lipkin-Nogami methods were used to calculate the quasiparticle energies and rotational bands of nuclei in the nobelium region. Starting from the most recent Skyrme parametrization, UNEDF1, the spin-orbit coupling constants and pairing strengths have been tuned, so as to achieve a better agreement with the excitation spectra and odd-even mass differences in 251Cf and 249Bk.

Results: The quasiparticle properties of 251Cf and 249Bk were very well reproduced. At the same time, crucial deformed neutron and proton shell gaps open up at N=152 and Z=100, respectively. Rotational bands in Fm, No, and Rf isotopes, where experimental data are available, were also fairly well described. To help future improvements towards a more precise description, small deficiencies of the approach were carefully identified.

Conclusions: In the Z≈100 mass region, larger spin-orbit strengths than those from global adjustments lead to improved agreement with data. Puzzling effects of particle-number restoration on the calculated moment of inertia, at odds with the experimental behavior, require further scrutiny.