78 research outputs found
Scaling Calculation of Isoscalar Giant Resonances in Relativistic Thomas-Fermi Theory
We derive analytical expressions for the excitation energy of the isoscalar
giant monopole and quadrupole resonances in finite nuclei, by using the scaling
method and the extended Thomas-Fermi approach to relativistic mean field
theory. We study the ability of several non-linear sigma-omega parameter sets
of common use in reproducing the experimental data. For monopole oscillations
the calculations agree better with experiment when the nuclear matter
incompressibility of the relativistic interaction lies in the range 220-260
MeV. The breathing-mode energies of the scaling method compare satisfactorily
with those obtained in relativistic RPA and time-dependent mean field
calculations. For quadrupole oscillations all the analyzed non-linear parameter
sets reproduce the empirical trends reasonably well.Comment: 41 pages, LaTeX, 4 eps figure
Nuclear surface properties in relativistic effective field theory
We perform Hartree calculations of symmetric and asymmetric semi-infinite
nuclear matter in the framework of relativistic models based on effective
hadronic field theories as recently proposed in the literature. In addition to
the conventional cubic and quartic scalar self-interactions, the extended
models incorporate a quartic vector self-interaction, scalar-vector
non-linearities and tensor couplings of the vector mesons. We investigate the
implications of these terms on nuclear surface properties such as the surface
energy coefficient, surface thickness, surface stiffness coefficient, neutron
skin thickness and the spin-orbit force.Comment: 30 pages, 15 figures. Submitted to Nuclear Physics
Surface Incompressibility from Semiclassical Relativistic Mean Field Calculations
By using the scaling method and the Thomas-Fermi and Extended Thomas-Fermi
approaches to Relativistic Mean Field Theory the surface contribution to the
leptodermous expansion of the finite nuclei incompressibility has been
self-consistently computed. The validity of the simplest expansion, which
contains volume, volume-symmetry, surface and Coulomb terms, is examined by
comparing it with self-consistent results of the finite nuclei
incompressibility for some currently used non-linear sigma-omega parameter
sets. A numerical estimate of higher-order contributions to the leptodermous
expansion, namely the curvature and surface-symmetry terms, is made.Comment: 18 pages, REVTeX, 3 eps figures, changed conten
Pairing Properties In Relativistic Mean Field Models Obtained From Effective Field Theory
We apply recently developed effective field theory nuclear models in mean
field approximation (parameter sets G1 and G2) to describe ground-state
properties of nuclei from the valley of -stability up to the drip lines.
For faster calculations of open-shell nuclei we employ a modified BCS approach
which takes into account quasi-bound levels owing to their centrifugal barrier,
with a constant pairing strength. We test this simple prescription by comparing
with available Hartree-plus-Bogoliubov results. Using the new effective
parameter sets we then compute separation energies, density distributions and
spin--orbit potentials in isotopic (isotonic) chains of nuclei with magic
neutron (proton) numbers. The new forces describe the experimental systematics
similarly to conventional non-linear relativistic force
parameters like NL3.Comment: 29 pages, 17 figures, accepted for publication in PR
Scaling in Relativistic Thomas-Fermi Approach for Nuclei
By using the scaling method we derive the virial theorem for the relativistic
mean field model of nuclei treated in the Thomas-Fermi approach. The
Thomas-Fermi solutions statisfy the stability condition against scaling. We
apply the formalism to study the excitation energy of the breathing mode in
finite nuclei with several relativistic parameter sets of common use.Comment: 13 page
Pairing and continuum effects in nuclei close to the drip line
The Hartree-Fock-Bogoliubov (HFB) equations in coordinate representation are
solved exactly, i.e., with correct asymptotic boundary conditions for the
continuous spectrum. The calculations are preformed with effective Skyrme
interactions. The exact HFB solutions are compared with HFB calculations based
on box boundary conditions and with resonant continuum Hartree-Fock-BCS
(HF-BCS) results. The comparison is done for the neutron-rich Ni isotopes. It
is shown that close to the drip line the amount of pairing correlations depends
on how the continuum coupling is treated. On the other hand, the resonant
continuum HF-BCS results are generally close to those of HFB even in
neutron-rich nuclei.Comment: 9 figures, corrected ref.
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