180 research outputs found
Global Properties of Spherical Nuclei Obtained from Hartree-Fock-Bogoliubov Calculations with the Gogny Force
Selfconsistent Hartree-Fock-Bogoliubov (HFB) calculations have been performed
with the Gogny force for nuclei along several constant Z and constant N chains,
with the purpose of extracting the macroscopic part of the binding energy using
the Strutinsky prescription. The macroscopic energy obtained in this way is
compared to current liquid drop formulas. The evolution of the single particle
levels derived from the HFB calculations along the constant Z and constant N
chains and the variations of the different kinds of nuclear radii are also
analysed. Those radii are shown to follow isospin-dependent three parameter
laws close to the phenomenological formulas which reproduce experimental data.Comment: 17 pages in LaTeX and 17 figures in eps. Phys. Rev. C, accepted for
publicatio
The Neutron Halo in Heavy Nuclei Calculated with the Gogny Force
The proton and neutron density distributions, one- and two-neutron separation
energies and radii of nuclei for which neutron halos are experimentally
observed, are calculated using the self-consistent Hartree-Fock-Bogoliubov
method with the effective interaction of Gogny. Halo factors are evaluated
assuming hydrogen-like antiproton wave functions. The factors agree well with
experimental data. They are close to those obtained with Skyrme forces and with
the relativistic mean field approach.Comment: 13 pages in Latex and 17 figures in ep
Giant resonances in exotic spherical nuclei within the RPA approach with the Gogny force
Theoretical results for giant resonances in the three doubly magic exotic
nuclei Ni, Sn and Sn are obtained from Hartree-Fock (HF)
plus Random Phase Approximation (RPA) calculations using the D1S
parametrization of the Gogny two-body effective interaction. Special attention
is paid to full consistency between the HF field and the RPA particle-hole
residual interaction. The results for the exotic nuclei, on average, appear
similar to those of stable ones, especially for quadrupole and octupole states.
More exotic systems have to be studied in order to confirm such a trend. The
low energy of the monopole resonance in Ni suggests that the compression
modulus in this neutron rich nucleus is lower than the one of stable ones.Comment: 16 pages, 10 figure
Deformed Hartree-Fock Calculation of Proton-Rich Nuclei
We perform Hartree-Fock+BCS calculations for even-even nuclei with 2 <= Z <=
82 and N ranging from outside the proton drip line to the experimental frontier
on the neutron-rich side. The ground state solutions are obtained for 737
nuclei, together with shape-coexistence solutions for 480 nuclei. Our method
features the Cartesian-mesh representation of single-particle wavefunctions,
which is advantageous in treating nucleon skins and exotic shapes. The results
are compared with those of the finite-range droplet model of Moller et al. as
well as the experimental values.Comment: 7 pages Latex, 5 postscript figures appended as uufil
Pairing correlation in nuclear matter from Skyrme force
The properties of pairing correlation in nuclear matter are investigated by
using various versions of Skyrme forces. Truncation of states involving pairing
correlation, necessary due to zero range nature of the Skyrme force, is
discussed in detail. A plateau appears in pairing gap versus cutoff for each
force. We propose to choose the cutoff parameter in the middle of the plateau
so that the parameterization is independent of nuclides.Comment: Latex, Submitted to Phys. Lett. B, 8 pages, 1 table and 3 uuencoded
postscript figures (modified) included, UT-Komaba 94-
Analytically Solvable Mean-Field Potential for Stable and Exotic Nuclei
Slater determinants built from the single-particle wave functions of the
analytically solvable Ginocchio potential are used to approximate the
self-consistent Hartree-Fock solutions for the ground states of nuclei. The
results indicate that the Ginocchio potential provides a good parametrization
of the nuclear mean field for a wide range of nuclei, including those at the
limit of particle stability.Comment: 11 pages, LateX, 3 postscript figures. Submitted to Physical Review
Letter
Coulomb exchange and pairing contributions in nuclear Hartree-Fock-Bogoliubov calculations with the Gogny force
We present exact Hartree-Fock-Bogoliubov calculations with the finite range
density dependent Gogny force using a triaxial basis. For the first time, all
contributions to the Pairing and Fock Fields arising from the Gogny and Coulomb
interactions as well as the two-body correction of the kinetic energy have been
calculated in this basis. We analyze the relevance of these terms in different
regions of the periodic table at zero and high angular momentum. The validity
of commonly used approximations that neglect different terms in the variational
equations is also checked. We find a decrease of the proton pairing energies
mainly due to a Coulomb antipairing effect.Comment: 32 pages, 12 figures. In press in Nucl. Physics
Continuum HFB calculations with finite range pairing interactions
A new method of calculating pairing correlations in coordinate space with
finite range interactions is presented. In the Hartree-Fock-Bogoliubov (HFB)
approach the mean field part is derived from a Skyrme-type force whereas the
pairing field is constructed with a Gogny force. An iterative scheme is used
for solving the integro-differential HFB equations via the introduction of a
local equivalent potential. The method is illustrated on the case of the
nucleus C. It is shown that the results are insensitive to the cut off
value in the quasiparticle spectrum if this value is above 100 MeV.Comment: 3 figures, in press, Phys. Lett.
Gaussian matrix elements in a cylindrical harmonic oscillator basis
We derive a formalism, the separation method, for the efficient and accurate
calculation of two-body matrix elements for a Gaussian potential in the
cylindrical harmonic-oscillator basis. This formalism is of critical importance
for Hartree-Fock and Hartree-Fock-Bogoliubov calculations in deformed nuclei
using realistic, finite-range effective interactions between nucleons. The
results given here are also relevant for microscopic many-body calculations in
atomic and molecular physics, as the formalism can be applied to other types of
interactions beyond the Gaussian form. The derivation is presented in great
detail to emphasize the methodology, which relies on generating functions. The
resulting analytical expressions for the Gaussian matrix elements are checked
for speed and accuracy as a function of the number of oscillator shells and
against direct numerical integration.Comment: 55 pages, 9 figures, Computer Physics Communications 180, 1013-1040
(2009
Mean-field Based Approaches to Pairing Correlations in Atomic Nuclei
The evolution of the pairing correlations from closed shell to middle shell
nuclei is analyzed with a Finite Range Density Dependent interaction in the Sn
isotopes. As theoretical approaches we use the Hartree-Fock-Bogoliubov, the
Lipkin-Nogami, their particle number projected counterparts and the full
variation after particle number projection method. We find that whereas all
approaches succeed rather well in the description of the total energy they
differ significantly in the pairing correlation content of the wave functions.
The description of the evolution from the weak to the strong pairing regime is
also approach dependent, specially at shell closure.Comment: 14 pages, 5 figure
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