1,018 research outputs found
Structure of the inner crust of neutron stars: crystal lattice or disordered phase ?
We investigate the inner crust structure of neutron stars using the
Skyrme-Hartree-Fock approach with the Coulomb interaction treated beyond the
Wigner-Seitz approximation. Our results suggest that the shell effects
associated with unbound neutrons play an important role and, in particular,
lead to complicated phase transition pattern between various nuclear phases (as
a function of the density). Namely, we show that the relative energies of
different phases are rapidly oscillating functions of the neutron density. In
the semiclassical approach this behavior is explained as an interference effect
due to periodic orbits of similar lengths. We discuss also the dependence of
the shell effects on pairing correlations.Comment: 20 pages, 5 figure
Properties of nuclei in the neutron star crust
In the present study we investigate the static properties of nuclei in the
inner crust of neutron stars. Using the Hartree-Fock method in coordinate
space, together with the semiclassical approximation, we examine the patterns
of phase transitions.Comment: 6 pages, 1 figure, presented at the Nuclear Many-Body Problem 2001 -
NATO Advanced Research Workshop, June 1-6, Brijuni, Croatia, 200
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
Solution of the Skyrme HF+BCS equation on a 3D mesh. II. A new version of the Ev8 code
We describe a new version of the EV8 code that solves the nuclear
Skyrme-Hartree-Fock+BCS problem using a 3-dimensional cartesian mesh. Several
new features have been implemented with respect to the earlier version
published in 2005. In particular, the numerical accuracy has been improved for
a given mesh size by (i) implementing a new solver to determine the Coulomb
potential for protons (ii) implementing a more precise method to calculate the
derivatives on a mesh that had already been implemented earlier in our
beyond-mean-field codes. The code has been made very flexible to enable the use
of a large variety of Skyrme energy density functionals that have been
introduced in the last years. Finally, the treatment of the constraints that
can be introduced in the mean-field equations has been improved. The code Ev8
is today the tool of choice to study the variation of the energy of a nucleus
from its ground state to very elongated or triaxial deformations with a
well-controlled accuracy.Comment: 24 pages, 3 figure
Nuclear tetrahedral configurations at spin zero
The possibility of the existence of stable tetrahedral deformations at spin
zero is investigated using the Skyrme-HFBCS approach and the generator
coordinate method (GCM). The study is limited to nuclei in which the
tetrahedral mode has been predicted to be favored on the basis of non
self-consistent models. Our results indicate that a clear identification of
tetrahedral deformations is unlikely as they are strongly mixed with the axial
octupole mode. However, the excitation energies related to the tetrahedral mode
are systematically lower than those of the axial octupole mode in all the
nuclei included in this study.Comment: 10 pages, 4 figure
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.
Quantum fluctuations and stability of tetrahedral deformations in atomic nuclei
The possible existence of stable axial octupole and tetrahedral deformations
is investigated in Zr and Zr. HFBCS calculations with parity
projection have been performed for various parametrizations of the Skyrme
energy functional. The correlation and excitation energies of negative parity
states associated with shape fluctuations have been obtained using the
generator coordinate method (GCM). The results indicate that in these nuclei
both the axial octupole and tetrahedral deformations are of dynamic character
and possess similar characteristics. Various Skyrme forces give consistent
results as a function of these two octupole degrees of freedom both at the
mean-field level as well as for configuration mixing calculations.Comment: 8 pages, 4 figures, submitted to IJMP
Beyond-mean-field study of the possible "bubble" structure of 34Si
Recent self-consistent mean-field calculations predict a substantial
depletion of the proton density in the interior of 34Si. In the present study,
we investigate how correlations beyond the mean field modify this finding. The
framework of the calculation is a particle-number and angular-momentum
projected Generator Coordinate Method based on
Hartree-Fock-Bogoliubov+Lipkin-Nogami states with axial quadrupole deformation.
The parametrization SLy4 of the Skyrme energy density functional is used
together with a density-dependent pairing energy functional. For the first
time, the generator coordinate method is applied to the calculation of charge
and transition densities. The impact of pairing correlations, symmetry
restorations and shape mixing on the density profile is analyzed step by step.
All these effects significantly alter the radial density profile, and tend to
bring it closer to a Fermi-type density distribution.Comment: 9 pages, 7 figure
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