14 research outputs found
Angular momentum projection of cranked Hartree-Fock states: Application to terminating bands in A~44 nuclei
We present the first systematic calculations based on the angular-momentum
projection of cranked Slater determinants. We propose the Iy --> I scheme, by
which one projects the angular momentum I from the 1D cranked state constrained
to the average spin projection of =I. Calculations performed for the
rotational band in 46Ti show that the AMP Iy --> I scheme offers a natural
mechanism for correcting the cranking moment of inertia at low-spins and
shifting the terminating state up by ~2 MeV, in accordance with data. We also
apply this scheme to high-spin states near the band termination in A~44 nuclei,
and compare results thereof with experimental data, shell-model calculations,
and results of the approximate analytical symmetry-restoration method proposed
previously.Comment: 9 RevTeX pages, 8 EPS figures, submitted to Physical Review
Solution of the Skyrme-Hartree-Fock-Bogolyubov equations in the Cartesian deformed harmonic-oscillator basis. (VI) HFODD (v2.38j): a new version of the program
We describe the new version (v2.38j) of the code HFODD which solves the
nuclear Skyrme-Hartree-Fock or Skyrme-Hartree-Fock-Bogolyubov problem by using
the Cartesian deformed harmonic-oscillator basis. In the new version, we have
implemented: (i) projection on good angular momentum (for the Hartree-Fock
states), (ii) calculation of the GCM kernels, (iii) calculation of matrix
elements of the Yukawa interaction, (iv) the BCS solutions for state-dependent
pairing gaps, (v) the HFB solutions for broken simplex symmetry, (vi)
calculation of Bohr deformation parameters, (vii) constraints on the Schiff
moments and scalar multipole moments, (viii) the D2h transformations and
rotations of wave functions, (ix) quasiparticle blocking for the HFB solutions
in odd and odd-odd nuclei, (x) the Broyden method to accelerate the
convergence, (xi) the Lipkin-Nogami method to treat pairing correlations, (xii)
the exact Coulomb exchange term, (xiii) several utility options, and we have
corrected two insignificant errors.Comment: 45 LaTeX pages, 4 figures, submitted to Computer Physics
Communication
Large-Scale Self-Consistent Nuclear Mass Calculations
The program of systematic large-scale self-consistent nuclear mass
calculations that is based on the nuclear density functional theory represents
a rich scientific agenda that is closely aligned with the main research
directions in modern nuclear structure and astrophysics, especially the
radioactive nuclear beam physics. The quest for the microscopic understanding
of the phenomenon of nuclear binding represents, in fact, a number of
fundamental and crucial questions of the quantum many-body problem, including
the proper treatment of correlations and dynamics in the presence of symmetry
breaking. Recent advances and open problems in the field of nuclear mass
calculations are presented and discussed.Comment: 21 pages, 5 figures, submitted to International Journal of Mass
Spectrometr
On the origin of the anomalous behaviour of 2+ excitation energies in the neutron-rich Cd isotopes
Recent experimental results obtained using decay and isomer
spectroscopy indicate an unusual behaviour of the energies of the first excited
2 states in neutron-rich Cd isotopes approaching the N=82 shell closure.
To explain the unexpected trend, changes of the nuclear structure far-off
stability have been suggested, namely a quenching of the N=82 shell gap already
in Cd, only two proton holes away from doubly magic Sn. We
study the behaviour of the 2 energies in the Cd isotopes from N=50 to N=82,
i.e. across the entire span of a major neutron shell using modern beyond mean
field techniques and the Gogny force. We demonstrate that the observed low
2 excitation energy in Cd close to the N=82 shell closure is a
consequence of the doubly magic character of this nucleus for oblate
deformation favoring thereby prolate configurations rather than spherical ones.Comment: 10 pages, 4 figures, to be publised in Phys. Lett.
Solution of the Skyrme-Hartree-Fock-Bogolyubov equations in the Cartesian deformed harmonic-oscillator basis. (VII) HFODD (v2.49t): a new version of the program
We describe the new version (v2.49t) of the code HFODD which solves the
nuclear Skyrme Hartree-Fock (HF) or Skyrme Hartree-Fock-Bogolyubov (HFB)
problem by using the Cartesian deformed harmonic-oscillator basis. In the new
version, we have implemented the following physics features: (i) the isospin
mixing and projection, (ii) the finite temperature formalism for the HFB and
HF+BCS methods, (iii) the Lipkin translational energy correction method, (iv)
the calculation of the shell correction. A number of specific numerical methods
have also been implemented in order to deal with large-scale multi-constraint
calculations and hardware limitations: (i) the two-basis method for the HFB
method, (ii) the Augmented Lagrangian Method (ALM) for multi-constraint
calculations, (iii) the linear constraint method based on the approximation of
the RPA matrix for multi-constraint calculations, (iv) an interface with the
axial and parity-conserving Skyrme-HFB code HFBTHO, (v) the mixing of the HF or
HFB matrix elements instead of the HF fields. Special care has been paid to
using the code on massively parallel leadership class computers. For this
purpose, the following features are now available with this version: (i) the
Message Passing Interface (MPI) framework, (ii) scalable input data routines,
(iii) multi-threading via OpenMP pragmas, (iv) parallel diagonalization of the
HFB matrix in the simplex breaking case using the ScaLAPACK library. Finally,
several little significant errors of the previous published version were
corrected.Comment: Accepted for publication to Computer Physics Communications. Program
files re-submitted to Comp. Phys. Comm. Program Library after correction of
several minor bug
Spin-orbit term and spin-fields: extension of Skyrme-force induced local energy density approach
A systematic study of terminating states in A50 mass region using the
self-consistent Skyrme-Hartree-Fock model is presented. The objective is to
demonstrate that the terminating states, due to their intrinsic simplicity,
offer unique and so far unexplored opportunities to study different aspects of
the effective NN interaction or nuclear local energy density functional. In
particular, we demonstrate that the agreement of the calculations to the data
depend on the spin fields and the spin-orbit term which, in turn, allows to
constrain the appropriate Landau parameters and the strength of the spin-orbit
potential.Comment: 23 pages, 9 figures, submitted to PR
Multiple shape coexistence in the nucleus Zr
We study the low-lying energy spectrum of the rp-process waiting point
nucleus 80Zr with state-of-the-art beyond mean field methods with the Gogny D1S
interaction. Symmetry restoration and configuration mixing of axial and
triaxial shapes are included in the calculations. Five 0+ states corresponding
to different nuclear shapes are obtained below 2.25 MeV and several rotational
and {\gamma}- bands built upon them are identified. Nevertheless, these states
do not modify the {\beta}-decay half-life having a negligible effect in the
rp-process. A good agreement with the available experimental data is obtained.Comment: 6 pages, 3 figures, submitted to Physics Letters
Properties of odd nuclei and the impact of time-odd mean fields: A systematic Skyrme-Hartree-Fock analysis
We present a systematic analysis of the description of odd nuclei by the
Skyrme-Hartree-Fock approach augmented with pairing in BCS approximation and
blocking of the odd nucleon. Current and spin densities in the Skyrme
functional produce time-odd mean fields (TOMF) for odd nuclei. Their effect on
basic properties (binding energies, odd-even staggering, separation energies
and spectra) is investigated for the three Skyrme parameterizations SkI3, SLy6,
and SV-bas. About 1300 spherical and axially-deformed odd nuclei with 16 < Z <
92 are considered. The calculations demonstrate that the TOMF effect is
generally small, although not fully negligible. The influence of the Skyrme
parameterization and the consistency of the calculations are much more
important. With a proper choice of the parameterization, a good description of
binding energies and their differences is obtained, comparable to that for even
nuclei. The description of low-energy excitation spectra of odd nuclei is of
varying quality depending on the nucleus
Using genetic and ant algorithms to solve transport problems
W pracy przedstawiono możliwości zastosowania metaheurystyk w transporcie. Przy użyciu algorytmu genetycznego i mrówkowego dokonano optymalizacji długości trasy przejazdu, a rezultaty porównano ze znanymi wynikami. Przedstawiono również próbę optymalizacji tras ze względu na czas trwania przejazdu.The paper presents possibilities to employ metaheuristics in transport. The research involved using genetic and ant algorithm to optimise drive/ride route length, and obtained results were compared to known results. Moreover, the paper presents an effort to optimise routes with regard to drive duration