421 research outputs found
Beyond-mean-field-model analysis of low-spin normal-deformed and superdeformed collective states of S32, Ar36, Ar38 and Ca40
We investigate the coexistence of spherical, deformed and superdeformed
states at low spin in S32, Ar36, Ar38 and Ca40. The microscopic states are
constructed by configuration mixing of BCS states projected on good particle
number and angular momentum. The BCS states are themselves obtained from
Hartree-Fock BCS calculations using the Skyrme interaction SLy6 for the
particle-hole channel, and a density-dependent contact force in the pairing
channel. The same interaction is used within the Generator Coordinate Method to
determine the configuration mixing and calculate the properties of even-spin
states with positive parity. Our calculations underestimate moments of inertia.
Nevertheless, for the four nuclei, the global structural properties of the
states of normal deformation as well as the recently discovered superdeformed
bands up to spin 6 are correctly reproduced with regard to both the energies
and the transition rates.Comment: 14 pages revtex4, 15 eps figures, 8 table
Superdeformed Bands of Odd Nuclei in A=190 Region in the Quasiparticle Picture
We study the properties of the superdeformed (SD) bands of 195Pb and 193Hg by
the cranked Hartree-Fock-Bogoliubov method. Our calculations reproduce the flat
behavior of the dynamical moment of inertia of two of the SD bands of 195Pb
measured recently. We discuss possible configuration assignments for the
observed bands 3 and 4 of 195Pb. We also calculate the two interacting SD bands
of 193Hg. Our analysis confirms the superiority of a density-dependent pairing
force over a seniority pairing interaction.Comment: 12 pages, 5 Postscript figures, submitted to Phys.Rev.
Large-amplitude Qn-Qp collectivity in the neutron-rich oxygen isotope 20O
By means of HFB calculations with independent constraints on axial neutron
and proton quadrupole moments Q_n and Q_p, we investigate the large amplitude
isoscalar and isovector deformation properties of the neutron-rich isotope 20O.
Using the particle-number and angular-momentum projected Generator Coordinate
Method, we analyze the collective dynamics in the {Q_n, Q_p} plane. The
parameterization SLy4 of the Skyrme interaction is used for all calculations in
connection with a density-dependent zero-range pairing interaction. Our results
show that already for this moderately neutron-rich nucleus the transition
moments are modified when independent neutron and proton collective dynamics
are allowed.Comment: 8 pages REVTEX, 5 eps figure
GCM Analysis of the collective properties of lead isotopes with exact projection on particle numbers
We present a microscopic analysis of the collective behaviour of the lead
isotopes in the vicinity of Pb208. In this study, we rely on a coherent
approach based on the Generator Coordinate Method including exact projection on
N and Z numbers within a collective space generated by means of the constrained
Hartree-Fock BCS method. With the same Hamiltonian used in HF+BCS calculations,
we have performed a comprehensive study including monopole, quadrupole and
octupole excitations as well as pairing vibrations. We find that, for the
considered nuclei, the collective modes which modify the most the conclusions
drawn from the mean-field theory are the octupole and pairing vibrations.Comment: 10 pages LATEX, 8 figures, submitted to EPJ
Couplage des mouvements collectifs et individuels : Théorie de champ moyen : résultats et développements
École thématiqu
Extended Skyrme interaction (II): ground state of nuclei and of nuclear matter
We study the effect of time-odd components of the Skyrme energy density
functionals on the ground state of finite nuclei and in nuclear matter. The
spin-density dependent terms, which have been recently proposed as an extension
of the standard Skyrme interaction, are shown to change the total binding
energy of odd-nuclei by only few tenths of keV, while the time-odd components
of standard Skyrme interactions give an effect that is larger by one order of
magnitude. The HFB-17 mass formula based on a Skyrme parametrization is
adjusted including the new spin-density dependent terms. A comprehensive study
of binding energies in the whole mass table of 2149 nuclei gives a root mean
square (rms) deviation of 0.575 MeV between experimental data and the
calculated results, which is slightly better than the original HFB-17 mass
formula. From the analysis of the spin instabilities of nuclear matter,
restrictions on the parameters governing the spin-density dependent terms are
evaluated. We conclude that with the extended Skyrme interaction, the Landau
parameters and could be tuned with a large flexibility
without changing the ground-state properties in nuclei and in nuclear matter.Comment: 18 pages, 4 tables, 6 figure
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