Publications (17)36.41 Total impact
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ABSTRACT: The extrapolation of selfconsistent nuclear meanfield models to the region of superheavy elements is discussed within the framework of SkyrmeHartreeFock and relativistic meanfield models. We present results for a large number of current parameterizations and find conflicting predictions for the next major shell closures, related to the effective mass and spinorbit interaction. A critical examination of the performance of the various models prefers Z = 120, N = 172 as the doublymagic superheavy nucleus.  [Show abstract] [Hide abstract]
ABSTRACT: . The extrapolation of selfconsistent nu lear mean.eld models to the region of superheavy elements is discussed within the framework of Skyrme Hartree Fo k and relativistic mean.eld models.We present results for spheri cal and deformed shell losures for a large number of current parameterizations and potential energy surfaces of a few selected nuclei.We .nd con .icting pre dictions for the next major shell closures which are related to the e .ective mass and spinorbit interaction. A criti al examination of the performan e of the various models with respect to the key features important for superheavy nuclei prefers Z =120,N =172 to be the doublymagi superheavy nucleus.  [Show abstract] [Hide abstract]
ABSTRACT: We discuss the pairing gap, a measure for nuclear pairing correlations, in chains of spherical, semimagic nuclei in the framework of selfconsistent nuclear meanfield models. The equations for the conventional BCS model and the approximate projectionbeforevariation LipkinNogami method are formulated in terms of local density functionals for the effective interaction. We calculate the LipkinNogami corrections of both the meanfield energy and the pairing energy. Various definitions of the pairing gap are discussed as threepoint, fourpoint and fivepoint massdifference formulae, averaged matrix elements of the pairing potential, and singlequasiparticle energies. Experimental values for the pairing gap are compared with calculations employing both a delta pairing force and a densitydependent delta interaction in the BCS and LipkinNogami model. Oddmass nuclei are calculated in the spherical blocking approximation which neglects part of the the core polarization in the odd nucleus. We find that the fivepoint mass difference formula gives a very robust description of the oddeven staggering, other approximations for the gap may differ from that up to 30% for certain nuclei.  [Show abstract] [Hide abstract]
ABSTRACT: We study the influence of the scheme for the correction for spurious center–of–mass motion on the fit of effective interactions for self–consistent nuclear mean–field calculations. We find that interactions with very simple center–of–mass correction have significantly larger surface coefficients than interactions for which the center–of–mass correction was calculated for the actual many–body state during the fit. The reason for that is that the effective interaction has to counteract the wrong trends with nucleon number of all simplified schemes for center–of–mass correction which puts a wrong trend with mass number into the effective interaction itself. The effect becomes clearly visible when looking at the deformation energy of largely deformed systems, e.g. superdeformed states or fission barriers of heavy nuclei. 
Article: Pairing Gap and Polarisation Effects
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ABSTRACT: The phenomenological adjustment of the nuclear pairing strength is usually performed with respect to the oddeven staggering of the binding energies. We find that the results strongly depend on the way in which the ground states of the odd nuclei are computed. A thorough calculation including all timeeven and timeodd polarisation effects induced by the odd nucleon produces about 30% reduced oddeven staggering as compared to the standard spherical calculations in the relativistic meanfield model. The pairing strength must be enhanced by about 20% to compensate for that effect. The enhanced strength has dramatic consequences for the predicted deformation properties of the underlying meanfield models, possibly implying that new adjustments of their parameters become necessary as well.  [Show abstract] [Hide abstract]
ABSTRACT: We study the influence of the scheme for the correction for spurious centerofmass motion on the fit of effective interactions for selfconsistent nuclear meanfield calculations. We find that interactions with very simple centerofmass correction have significantly larger surface coefficients than interactions for which the centerofmass correction was calculated for the actual manybody state during the fit. The reason for that is that the effective interaction has to counteract the wrong trends with nucleon number of all simplified schemes for centerofmass correction which puts a wrong trend with mass number into the effective interaction itself. The effect becomes clearly visible when looking at the deformation energy of largely deformed systems, e.g. superdeformed states or fission barriers of heavy nuclei.  [Show abstract] [Hide abstract]
ABSTRACT: We discuss two widely used nuclear meanfield models, the relativistic meanfield model and the (nonrelativistic) SkyrmeHartreeFock model, and their capability to describe exotic nuclei with emphasis on neutronrich tin isotopes and superheavy nuclei.  [Show abstract] [Hide abstract]
ABSTRACT: We study the extrapolation of nuclear shell structure to the region of superheavy nuclei in selfconsistent meanfield models  the SkyrmeHartreeFock approach and the relativistic meanfield model  using a large number of parameterizations. Results obtained with the FoldedYukawa potential are shown for comparison. We focus on differences in the isospin dependence of the spinorbit interaction and the effective mass between the models and their influence on singleparticle spectra. While all relativistic models give a reasonable description of spinorbit splittings, all nonrelativistic models show a wrong trend with mass number. The spinorbit splitting of heavy nuclei might be overestimated by 40%80%. Spherical doublymagic superheavy nuclei are found at (Z=114,N=184), (Z=120,N=172) or (Z=126,N=184) depending on the parameterization. The Z=114 proton shell closure, which is related to a large spinorbit splitting of proton 2f states, is predicted only by forces which by far overestimate the proton spinorbit splitting in Pb208. The Z=120 and N=172 shell closures predicted by the relativistic models and some Skyrme interactions are found to be related to a central depression of the nuclear density distribution. This effect cannot appear in macroscopicmicroscopic models which have a limited freedom for the density distribution only. In summary, our findings give a strong argument for (Z=120,N=172) to be the next spherical doublymagic superheavy nucleus. Comment: 22 pages REVTeX, 16 eps figures, accepted for publication in Phys. Rev. C  [Show abstract] [Hide abstract]
ABSTRACT: We investigate the structure of the potential energy surfaces of the superheavy nuclei 258Fm, 264Hs, (Z=112,N=166), (Z=114,N=184), and (Z=120,N=172) within the framework of selfconsistent nuclear models, i.e. the SkyrmeHartreeFock approach and the relativistic meanfield model. We compare results obtained with one representative parametrisation of each model which is successful in describing superheavy nuclei. We find systematic changes as compared to the potential energy surfaces of heavy nuclei in the uranium region: there is no sufficiently stable fission isomer any more, the importance of triaxial configurations to lower the first barrier fades away, and asymmetric fission paths compete down to rather small deformation. Comparing the two models, it turns out that the relativistic meanfield model gives generally smaller fission barriers.  [Show abstract] [Hide abstract]
ABSTRACT: The ground–state properties of superheavy nuclei are investigated within various parametrisations of relativistic and nonrelativistic nuclear mean–field models. The heaviest known even–even nuclei starting with Z = 98 are used as a benchmark to estimate the predictive power of the models and forces. From that starting point, deformed doubly magic nuclei are searched in the region 100 ≤ Z ≤ 130 and 142 ≤ N ≤ 190.  [Show abstract] [Hide abstract]
ABSTRACT: The relation between the singlenucleon spectra of doubly magic nuclei and the excitation energies of the neighboring odd nuclei is investigated within the framework of a relativistic meanfield model. Different levels of approximation (spherical, deformed with timereversal invariance, without symmetry constraints) are computed and compared. Symmetry breaking, although small, has a substantial effect on separation energies and shell gaps. But energy differences completely within occupied or within unoccupied states are rather robust and can be safely estimated from the mere singlenucleon spectra of the eveneven reference nucleus.  [Show abstract] [Hide abstract]
ABSTRACT: The shell structure of superheavy nuclei is investigated within various parametrizations of relativistic and nonrelativistic nuclear meanfield models. The heaviest known eveneven nuclei are used as a benchmark to estimate the predictive value of the models. From that starting point, spherical and deformed shell closures in the superheavy region are searched. © 1998 American Institute of Physics. 
Article: An HFB scheme in natural orbitals
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ABSTRACT: We present a formulation of the HartreeFockBogoliubov (HFB) equations which solves the problem directly in the basis of natural orbitals. This provides a very efficient scheme which is particularly suited for large scale calculations on coordinatespace grids.  [Show abstract] [Hide abstract]
ABSTRACT: The shell structure of superheavy nuclei is investigated within various parametrizations of relativistic and nonrelativistic nuclear meanfield models. The heaviest known eveneven nucleus ${}_{156}^{264}{\mathrm{Hs}}_{108}$ is used as a benchmark to estimate the predictive value of the models. From that starting point, doubly magic spherical nuclei are searched in the region $Z=110$${}140$ and $N=134$\char21{}$298$. They are found at $(Z=114,N=184)$, $(Z=120,N=172)$, or at $(Z=126,N=184)$, depending on the parametrization.  [Show abstract] [Hide abstract]
ABSTRACT: The shell structure of superheavy nuclei is investigated within various parametrizations of relativistic and nonrelativistic nuclear mean field models. The heaviest known eveneven nucleus 264Hs is used as a benchmark to estimate the predictive value of the models. From that starting point, doubly magic spherical nuclei are searched in the region Z=110140 and N=134298. They are found at (Z=114, N=184), (Z=120, N=172), or at (Z=126, N=184), depending on the parametrization.  [Show abstract] [Hide abstract]
ABSTRACT: The symmetric and asymmetric fission path for 240Pu, 232Th and 226Ra is investigated within the relativistic meanfield model. Standard parametrizations which are well fitted to nuclear groundstate properties are found to deliver reasonable qualitative and quantitative features of fission, comparable to similar nonrelativistic calculations. Furthermore, stable octupole deformations in the ground states of radium isotopes are investigated. They are found in a series of isotopes, qualitatively in agreement with nonrelativistic models. But the quantitative details differ amongst the models and between the various relativistic parametrizations.  [Show abstract] [Hide abstract]
ABSTRACT: Properties of protonrich nuclei around doubly magic 4828Ni20 are studied in the framework of the selfconsistent meanfield theory (HartreeFock, HartreeFockBogoliubov, and relativistic mean field). Various effective interactions are employed to investigate twoproton separation energies, deformations, singleparticle levels, proton average potentials, and diproton partial decay halflives in this mass region.
Publication Stats
1k  Citations  
36.41  Total Impact Points  
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Institutions

19982000

GoetheUniversität Frankfurt am Main
 Institut für Theoretische Physik (ITP)
Frankfurt am Main, Hesse, Germany


19961999

University Hospital Frankfurt
Frankfurt, Hesse, Germany
