R. Rodríguez-Guzmán

Charge radii and structural evolution in Sr, Zr, and Mo isotopes

The evolution of the ground-state nuclear shapes in neutron-rich Sr, Zr, and Mo isotopes, including both even-even and odd-A nuclei, is studied within a self-consistent mean-field approximati on based on the D1S Gogny interaction. Neutron separation energies and charge radii are calculated and compared with available data. A correlation between a shape transition and a discontinuity in those observables is found microscopically. While in Sr and Zr isotopes the steep behavior observed in the isotopic dependence of the charge radii is a consequence of a sharp prolate-oblate tran sition, the smooth behavior found in Mo isotopes has its origin in an emergent region of triaxiality.

Mean field study of structural changes in Pt isotopes with the Gogny interaction

The evolution of the nuclear shapes along the triaxial landscape is studied in the Pt isotopic chain using the self-consistent Hartree-Fock-Bogoliubov approximation based on the Gogny interaction. In addition to the parametrization D1S, the new incarnations D1N and D1M of this force are also included in our analysis to assess to which extent the predictions are independent of details of the effective interaction. The considered range of neutron numbers 88 N 126 includes prolate, triaxial, oblate, and spherical ground-state shapes and serves as a detailed comparison of the predictions obtained with the new sets D1N and D1M against the ones provided by the standard parametrization Gogny-D1S in a region of the nuclear landscape for which experimental and theoretical fingerprints of shape transitions have been found. Structural evolution along the Pt chain is discussed in terms of the deformation dependence of single-particle energies.

Signatures of shape transitions in odd-A neutron-rich rubidium isotopes

The isotopic evolution of the ground-state nuclear shapes and the systematics of one-quasiproton configurations are studied in odd-A Rubidium isotopes. We use a self-consistent Hartree-Fock-Bogoliubov formalism based on the Gogny energy density functional with two parametrizations, D1S and D1M, and implemented with the equal-filling approximation. We find clear signatures of a sharp shape transition at N=60 in both the charge radii and spin parity of the ground states, which are robust, consistent with each other, and in agreement with experiment. We point out that the combined analysis of these two observables could be used to predict unambiguously new regions where shape transitions might develop.

Systematics of one-quasiparticle configurations in neutron-rich odd Sr, Zr, and Mo isotopes with the Gogny energy density functional

The systematics of one-quasiparticle configurations in neutron-rich Sr, Zr, and Mo odd isotopes is studied within the Hartree-Fock-Bogoliubov plus equal filling approximation method preserving both axial and time-reversal symmetries. Calculations based on the Gogny energy density functional with both the standard D1S parametrization and the new D1M incarnation of this functional are included in our analysis. The nuclear deformation and shape coexistence inherent to this mass region are shown to play a relevant role in the understanding of the spectroscopic features of the ground and low-lying one-quasineutron states.

Dynamic versus static fission paths with realistic interactions

The properties of dynamic (least action) fission paths are analyzed and compared to the ones of the more traditional static (least energy) paths. Both the BCPM and Gogny D1M energy density functionals are used in the calculation of the HFB constrained configurations providing the potential energy and collective inertias. The action is computed as in the WKB method. A full variational search of the least-action path over the complete variational space of HFB wave functions is cumbersome and probably unnecessary if the relevant degrees of freedom are identified. In this paper, we consider the particle number fluctuation degree of freedom that explores the amount of pairing correlations in the wave function. For a given shape, the minimum action can be up a factor of three smaller than the action computed for the minimum energy state with the same shape. The impact of this reduction on the lifetimes is enormous and dramatically improves the agreement with experimental data in the few examples considered.

Structural evolution in Pt isotopes with the interacting boson model Hamiltonian derived from the Gogny energy density functional

This work was supported in part by a Grant-in-Aid for Scientific Research (A) 20244022 and by a Grant-in-Aid from JSPS (No. 217368). K.N. is supported by a JSPS program. The work of L.M.R and P.S was supported by MICINN (Spain) under research Grants No. FIS2008–01301, No. FPA2009-08958, and No. FIS2009-07277, as well as by Consolider-Ingenio 2010 Programs CPAN CSD2007-00042 and MULTIDARK CSD2009-00064. R.R. acknowledges the support received within the framework of the FIDIPRO program (Academy of Finland and University of Jyvaskyla¨)

E(5) and X(5) shape phase transitions within a Skyrme-Hartree-Fock + BCS approach

Self-consistent Skyrme-Hartree-Fock plus BCS calculations are performed to generate potential energy curves (PECs) in various chains of Pd, Xe, Ba, Nd, Sm, Gd, and Dy isotopes. The evolution of shapes with the number of nucleons is studied in a search for signatures of E(5) and X(5) critical point symmetries. It is shown that the energy barriers in the PECs are determined to a large extent by the treatment of the pairing correlations.

Collective structural evolution in neutron-rich Yb, Hf, W, Os and Pt isotopes

This work was supported in part by Grants-in-Aid for Scientific Research (A)No. 20244022 and No. 217368. Author K.N. acknowledges the support by the JSPS. The work of authors R.R., L.M.R, and P.Swas supported by MICINN (Spain) under Research Grants No. FIS2008-01301, No. FPA2009-08958, and No. FIS2009-07277, as well as by Consolider-Ingenio 2010 Programs CPAN CSD2007-00042 and MULTIDARK CSD2009-00064

Shape evolution in yttrium and niobium neutron-rich isotopes

This work was supported by MICINN (Spain) under Grants No. FIS2008-01301, No. FPA2009-08958, and No. FIS2009-07277 and Consolider-Ingenio 2010 Programs CPAN CSD2007-00042 and MULTIDARK CSD2009-00064.

Shape evolution and shape coexistence in Pt isotopes: comparing interacting boson model configuration mixing and Gogny mean-field energy surfaces

The evolution of the total energy surface and the nuclear shape in the isotopic chain Pt172-194 are studied in the framework of the interacting boson model, including configuration mixing. The results are compared with a self-consistent Hartree-Fock-Bogoliubov calculation using the Gogny-D1S interaction and a good agreement between both approaches is found. The evolution of the deformation parameters points towards the presence of two different coexisting configurations in the region 176 <= A <= 186.