Thomas Duguet

The tensor part of the Skyrme energy density functional. I. Spherical nuclei

We perform a systematic study of the impact of the J^2 tensor term in the Skyrme energy functional on properties of spherical nuclei. In the Skyrme energy functional, the tensor terms originate both from zero-range central and tensor forces. We build a set of 36 parameterizations, which covers a wide range of the parameter space of the isoscalar and isovector tensor term coupling constants, with a fit protocol very similar to that of the successful SLy parameterizations. We analyze the impact of the tensor terms on a large variety of observables in spherical mean-field calculations, such as the spin-orbit splittings and single-particle spectra of doubly-magic nuclei, the evolution of spin-orbit splittings along chains of semi-magic nuclei, mass residuals of spherical nuclei, and known anomalies of charge radii. Our main conclusion is that the currently used central and spin-orbit parts of the Skyrme energy density functional are not flexible enough to allow for the presence of large tensor terms.

Skyrme mean-field study of rotational bands in transfermium isotopes

Abstract Self-consistent mean field calculations with the SLy4 interaction and a density-dependent pairing force are presented for nuclei in the nobelium mass region. Predicted quasi-particle spectra are compared with experiment for the heaviest known odd N and odd Z nuclei. Spectra and rotational bands are presented for nuclei around 252,4No for which experiments are either planned or already running.

Chiral two- and three-nucleon forces along medium-mass isotope chains

V. Somà,1, 2, ∗ A. Cipollone,3 C. Barbieri,3, † P. Navrátil,4 and T. Duguet5, 6, ‡ 1Institut für Kernphysik, Technische Universität Darmstadt, 64289 Darmstadt, Germany 2ExtreMe Matter Institute EMMI, GSI Helmholtzzentrum für Schwerionenforschung GmbH, 64291 Darmstadt, Germany 3Department of Physics, University of Surrey, Guildford GU2 7XH, UK 4TRIUMF, 4004 Westbrook Mall, Vancouver, BC, V6T 2A3, Canada 5CEA-Saclay, IRFU/Service de Physique Nucléaire, 91191 Gif-sur-Yvette, France 6National Superconducting Cyclotron Laboratory and Department of Physics and Astronomy, Michigan State University, East Lansing, MI 48824, USA (Dated: December 10, 2013)

Tensor interaction contributions to single-particle energies

We calculate the contribution of the nucleon-nucleon tensor interaction to single-particle energies with finite-range G-matrix potentials and with zero-range Skyrme potentials. The Skx Skyrme parameters including the zero-range tensor terms with strengths calibrated to the finite-range results are refitted to nuclear properties. The fit allows the zero-range proton-neutron tensor interaction as calibrated to the finite-range potential results which gives the observed change in the single-particle gap {epsilon}(h{sub 11/2})-{epsilon}(g{sub 7/2}) going from {sup 114}Sn to {sup 132}Sn. However, the experimental l dependence of the spin-orbit splittings in {sup 132}Sn and {sup 208}Pb is not well described when the tensor is added, owing to a change in the radial dependence of the total spin-orbit potential. The gap shift and a good fit to the l dependence can be recovered when the like-particle tensor interaction is opposite in sign to that required for the G matrix.

Tensor part of the Skyrme energy density functional. II: Deformation properties of magic and semi-magic nuclei

We study systematically the impact of the time-even tensor terms of the Skyrme energy density functional, i.e., terms bilinear in the spin-current tensor density, on deformation properties of closed-shell nuclei corresponding to 20,28,40,50,82, and 126 neutron or proton shell closures. We compare results obtained with three different families of Skyrme parametrizations whose tensor terms have been adjusted on properties of spherical nuclei: (i) TIJ interactions proposed in the first article of this series [T. Lesinski et al., Phys. Rev. C 76, 014312 (2007)] that were constructed through a complete readjustment of the rest of the functional and (ii) parametrizations whose tensor terms have been added perturbatively to existing Skyrme interactions, with or without readjusting the spin-orbit coupling constant. We analyze in detail the mechanisms at play behind the impact of tensor terms on deformation properties and how studying the latter can help screen out unrealistic parametrizations. It is expected that findings of the present article are to a large extent independent of remaining deficiencies of the central and spin-orbit interactions and will be of great value for the construction of future, improved energy functionals.

Rotational properties of 252, 253, 254No:: influence of pairing correlations

Abstract Rotational bands of 252,253,254No and the fission barriers of 254No at spin 0 ℏ and 20 ℏ are calculated with the Hartree–Fock–Bogolyubov theory and the Lipkin–Nogami approximate particle number projection. The SLy4 Skyrme force is used in the particle–hole channel. A zero-range force with and without density-dependence is used in the particle–particle channel. The experimental ground state deformation ( Q 20 =32.8 b) is reproduced as well as the increase of the dynamical moment of inertia with frequency both for 252No and 254No. The rotational band of 253No is also calculated. Fission barriers of 254No at spin 0 ℏ and 20 ℏ show the robustness of shell-corrections against rotation in these heavy nuclei.

Isovector splitting of nucleon effective masses, ab initio benchmarks and extended stability criteria for Skyrme energy functionals

We study the effect of the splitting of neutron and proton effective masses with isospin asymmetry on the properties of the Skyrme energy density functional. We discuss the ability of the latter to predict observables of infinite matter and finite nuclei, paying particular attention to controlling the agreement with ab initio predictions of the spin-isospin content of the nuclear equation of state, as well as diagnosing the onset of finite size instabilities, which we find to be of critical importance. We show that these various constraints cannot be simultaneously fulfilled by the standard Skyrme force, calling at least for an extension of its P-wave part.

Pairing correlations. II.: Microscopic analysis of odd-even mass staggering in nuclei

The odd-even mass staggering in nuclei is analyzed in the context of self-consistent mean-field calculations, for spherical as well as for deformed nuclei. For these nuclei, the respective merits of the energy differences

Ab initio Gorkov-Green's function calculations of open-shell nuclei

{\ensuremath{\Delta}}^{(3)}

Pairing correlations. I. Description of odd nuclei in mean-field theories

and