The mass of odd-odd nuclei in microscopic mass models

Ryssens, W.; Scamps, G.; Grams, G.; Kullmann, I.; Bender, M.; Goriely, S.

doi:10.48550/arxiv.2211.03667

Cited by 1 publication

(7 citation statements)

References 19 publications

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“…This accuracy with respect to the RIPL-3 reference values is to the best of our knowledge unprecedented: other large-scale models achieve at best an rms deviation of about 0.6 MeV on the primary barriers for the same set of nuclei, with generally larger deviations between 0.7 and 1 MeV for secondary barriers and isomers [10,42,102,103]. A more detailed analysis and discussion of the fission properties of BSkG2 will be presented in a forthcoming paper [116].…”

Section: Parameter Values and Global Performancementioning

confidence: 90%

“…Since it vanishes for spherical nuclei, the vibrational correction for such nuclei is absorbed into the fitted force parameters. For a more detailed discussion of this term, which is crucial to our description of fission, we refer the reader to a forthcoming paper [116]. (2022) 58:246 2.2 Numerical treatment of ground states…”

Section: The Vibrational Correctionmentioning

confidence: 99%

“…Even individual calculations on such surfaces are more costly than a typical ground state calculation, as coordinate meshes should be enlarged to accommodate very elongated shapes [14] and reflection symmetry cannot be assumed along the entire fission path. The MOCCa code offers all the tools necessary for such calculations, whose technical aspects will be presented in the accompanying paper [116]. We will thus limit the present discussion to those technical aspects of the treatment of ground states that are different from the adjustment of BSkG1 as described in Ref.…”

Section: General Commentsmentioning

confidence: 99%

“…We stress, however, that octupole deformation is systematically explored in the calculations of fission barriers made during the parameter adjustment; the numerical choices for these will be detailed in Ref. [116].…”

Section: Self-consistent Symmetriesmentioning

confidence: 99%

“…Our calculation of fission barriers, performed to adjust this vibrational term, included octupole and triaxial degrees of freedom for systems with both even and odd numbers of nucleons. Due to this complexity, we postpone discussion of all our material related to fission to a forthcoming paper [116]. Here, we limit our discussion to the construction of the BSkG2 model and its description of both the ground state of finite nuclei and infinite nuclear matter.…”

Section: Introductionmentioning

confidence: 99%

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Skyrme–Hartree–Fock–Bogoliubov mass models on a 3D mesh: II. Time-reversal symmetry breaking

et al. 2022

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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 large-scale fits feasible, several symmetry restrictions are typically imposed on the nuclear configurations. One such example is time-reversal 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 odd-mass and odd-odd nuclei, which contribute to the total energy of such nuclei through so-called 'time-odd' terms. We present here the Skyrme-based 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 root-mean-square (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.

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