SkyrmeHartreeFockBogoliubov mass models on a 3D mesh: II. Timereversal symmetry breaking
Abstract
Models based on nuclear energy density functionals can provide access to a multitude of observables for thousands of nuclei in a single framework with microscopic foundations. Such models can rival the accuracy of more phenomenological approaches, but doing so requires adjusting parameters to thousands of nuclear masses. To keep such largescale fits feasible, several symmetry restrictions are typically imposed on the nuclear configurations. One such example is timereversal invariance, which is generally enforced via the Equal Filling Approximation (EFA). Here we lift this assumption, enabling us to access the spin and current densities in the ground states of oddmass and oddodd nuclei, which contribute to the total energy of such nuclei through socalled `timeodd' terms. We present here the Skyrmebased BSkG2 model whose parameters were adjusted to essentially all known nuclear masses without relying on the EFA, refining our earlier work [G. Scamps et al., EPJA 57, 333 (2021)]. Moving beyond ground state properties, we also incorporated information on the fission barriers of actinide nuclei in the parameter adjustment. The resulting model achieves a rootmeansquare (rms) deviation of (i) 0.678 MeV on 2457 known masses, (ii) 0.027 fm on 884 measured charge radii, (iii) 0.44 MeV and 0.47 MeV, respectively, on 45 reference values for primary and secondary fission barriers of actinide nuclei, and (iv) 0.49 MeV on 28 fission isomer excitation energies. We limit ourselves here to a description of the model and the study the impact of lifting the EFA on ground state properties such as binding energies, deformation and pairing, deferring a detailed discussion of fission to a forthcoming paper.
 Publication:

European Physical Journal A
 Pub Date:
 December 2022
 DOI:
 10.1140/epja/s10050022008945
 arXiv:
 arXiv:2208.06455
 Bibcode:
 2022EPJA...58..246R
 Keywords:

 Nuclear Theory
 EPrint:
 30 pages, 15 figures