arXiv subjects

A. Sánchez-Fernández

Publications and source records attributed to A. Sánchez-Fernández.

3 recordsLinked to original sources

arXiv2026

Skyrme-Hartree-Fock-Bogoliubov mass models on a 3D mesh: V. The N2LO extension of the Skyrme EDF

We present BSkG5, the latest entry in the Brussels-Skyrme-on-a-Grid (BSkG) series and the first large-scale nuclear structure model based on next-to-next-to-leading order (N2LO) Skyrme energy density functional (EDF). By extending the traditional Skyrme EDF ansatz with central terms containing up to four gradients, we are able to combine an excellent global description of nuclear ground state properties with a stiff equation of state for pure neutron matter that is consistent with all astronomical observations of neutron stars. More precisely, the new model matches the accuracy of earlier BSkG models but with two parameters less: we achieve root-mean-square deviations of 0.649 MeV for 2457 atomic masses, 0.0267 fm for 810 charge radii, and 0.43 MeV for 45 primary fission barriers of actinide nuclei. We demonstrate that the complexities of N2LO EDFs are not insurmountable, even for demanding many-body calculations.

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arXiv2025

Electromagnetic moments in the Sn-Gd region determined within nuclear DFT

Within the nuclear DFT framework, employing the Skyrme UNEDF1 functional and incorporating pairing correlations, we determined the spectroscopic electric quadrupole and magnetic dipole moments of the $\nu11/2^{-}$ and $\pi7/2^{+}$ configurations in heavy, deformed, open-shell odd nuclei with $50\leq Z \leq 64$. The notions of self-consistent shape and spin polarisations due to odd nucleons responsible for generating total electric quadrupole and magnetic dipole moments were transformed into detailed computational procedures. The alignment of intrinsic angular momentum along the axial symmetry axis, necessitating signature and time-reversal symmetry breaking, followed by the restoration of rotational symmetry, proved to be essential components of the method. In contrast, the restoration of particle number symmetry yields modifications of only about 1%. With the isovector spin-spin terms of the functional previously adjusted in near doubly magic nuclei across the mass chart, the calculations were parameter-free. Effective charges and $g$-factors were not employed. A reasonably good agreement was achieved between the calculated and measured electric quadrupole moments. A similarly fair description of the magnetic dipole moments was obtained for the intruder configurations $\nu11/2^{-}$ alongside a poor description of those for $\pi7/2^{+}$.

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arXiv2019

Variational approximations to exact solutions in shell-model valence spaces: calcium isotopes in the pf-shell

We study the performance of self-consistent mean-field and beyond-mean-field approximations in shell-model valence spaces. In particular, Hartree-Fock-Bogolyubov, particle-number variation after projection and projected generator coordinate methods are applied to obtain ground-state and excitation energies for even-even and odd-even Calcium isotopes in the pf-shell. The standard (and non-trivial) KB3G nuclear effective interaction has been used. The comparison with the exact solutions -- provided by the full diagonalization of the Hamiltonian -- shows an outstanding agreement when particle-number and angular-momentum restorations are performed and both quadrupole and neutron-neutron pairing degrees of freedom are explicitly explored as collective coordinates.

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