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Bimodal fission in the Skyrme-Hartree-Fock approach  [PDF]
A. Staszczak,J. Dobaczewski,W. Nazarewicz
Physics , 2006,
Abstract: Spontaneous-fission properties of 256Fm, 258Fm, and 260Fm isotopes are studied within the Skyrme-Hartree-Fock+BCS framework. In the particle-hole channel we take the Skyrme SkM* effective force, while in the particle-particle channel we employ the seniority pairing interaction. Three static fission paths for all investigated heavy fermium isotopes are found. The analysis of these fission modes allows to describe observed asymmetric fission of 256Fm, as well as bimodal fission of 258Fm and symmetric fission in 260Fm.
Fission of heavy $Λ$ hypernuclei with the Skyrme-Hartree-Fock approach  [PDF]
F. Minato,S. Chiba,K. Hagino
Physics , 2009, DOI: 10.1016/j.nuclphysa.2009.09.063
Abstract: Fission-related phenomena of heavy $\Lambda$ hypernuclei are discussed with the constraint Skyrme-Hartree-Fock+BCS (SHF+BCS) method, in which a similar Skyrme-type interaction is employed also for the interaction between a $\Lambda$ particle and a nucleon. Assuming that the $\Lambda$ particle adiabatically follows the fission motion, we discuss the fission barrier height of $^{239}_{\Lambda}$U. We find that the fission barrier height increases slightly when the $\Lambda$ particle occupies the lowest level. In this case, the $\Lambda$ particle is always attached to the heavier fission fragment. This indicates that one may produce heavy neutron-rich $\Lambda$ hypernuclei through fission, whose weak decay is helpful for the nuclear transmutation of long-lived fission products. We also discuss cases where the $\Lambda$ particle occupies a higher single-particle level.
Fission dynamics within time-dependent Hartree-Fock: deformation-induced fission  [PDF]
P. M. Goddard,P. D. Stevenson,A. Rios
Physics , 2015, DOI: 10.1103/PhysRevC.92.054610
Abstract: Background: Nuclear fission is a complex large-amplitude collective decay mode in heavy nuclei. Microscopic density functional studies of fission have previously concentrated on adiabatic approaches based on constrained static calculations ignoring dynamical excitations of the fissioning nucleus, and the daughter products. Purpose: To explore the ability of dynamic mean-field methods to describe fast fission processes beyond the fission barrier, using the nuclide $^{240}$Pu as an example. Methods: Time-dependent Hartree-Fock calculations based on the Skyrme interaction are used to calculate non-adiabatic fission paths, beginning from static constrained Hartree-Fock calculations. The properties of the dynamic states are interpreted in terms of the nature of their collective motion. Fission product properties are compared to data. Results: Parent nuclei constrained to begin dynamic evolution with a deformation less than the fission barrier exhibit giant-resonance-type behaviour. Those beginning just beyond the barrier explore large amplitude motion but do not fission, whereas those beginning beyond the two-fragment pathway crossing fission to final states which differ according to the exact initial deformation. Conclusions: Time-dependent Hartree-Fock is able to give a good qualitative and quantitative description of fast fission, provided one begins from a sufficiently deformed state.
Fission dynamics within time-dependent Hartree-Fock: boost-induced fission  [PDF]
P. M. Goddard,P. D. Stevenson,A. Rios
Physics , 2015,
Abstract: Background: Nuclear fission is a complex large-amplitude collective decay mode in heavy nuclei. Microscopic density functional studies of fission have previously concentrated on adiabatic approaches based on constrained static calculations ignoring dynamical excitations of the fissioning nucleus, and the daughter products. Purpose: To explore the ability of dynamic mean-field methods to describe induced fission processes, using quadrupole boosts in the nuclide $^{240}$Pu as an example. Methods: Quadrupole constrained Hartree-Fock calculations are used to create a potential energy surface. An isomeric state and a state beyond the second barrier peak are excited by means of instantaneous as well as temporally extended gauge boosts with quadrupole shapes. The subsequent deexcitation is studied in a time-dependent Hartree-Fock simulation, with emphasis on fissioned final states. The corresponding fission fragment mass numbers are studied. Results: In general, the energy deposited by the quadrupole boost is quickly absorbed by the nucleus. In instantaneous boosts, this leads to fast shape rearrangements and violent dynamics that can ultimately lead to fission. This is a qualitatively different process than the deformation-induced fission. Boosts induced within a finite time window excite the system in a relatively gentler way, and do induce fission but with a smaller energy deposition. Conclusions: The fission products obtained using boost-induced fission in time-dependent Hartree-Fock are more asymmetric than the fragments obtained in deformation-induced fission, or the corresponding adiabatic approaches.
Collective inertia and fission barriers within the Skyrme-Hartree-Fock theory  [PDF]
A. Baran,A. Staszczak,J. Dobaczewski,W. Nazarewicz
Physics , 2006, DOI: 10.1142/S0218301307005879
Abstract: Spontaneous fission barriers, quadrupole inertia, and zero-point quadrupole-energy corrections are calculated for 252,256,258Fm in the framework of the self-consistent Skyrme-Hartree-Fock+BCS theory. Two ways of computing dynamical inertia are employed: the Gaussian Overlap Approximation to the Generator Coordinate Method and cranking ansatz. The Skyrme results are compared with those of the Gogny-Hartree-Fock-Bogolyubov model.
Misfits in Skyrme-Hartree-Fock  [PDF]
J. Erler,P. Klüpfel,P. -G. Reinhard
Physics , 2010, DOI: 10.1088/0954-3899/37/6/064001
Abstract: We address very briefly five critical points in the context of the Skyrme-Hartree-Fock (SHF) scheme: 1) the impossibility to consider it as an interaction, 2) a possible inconsistency of correlation corrections as, e.g., the center-of-mass correction, 3) problems to describe the giant dipole resonance (GDR) simultaneously in light and heavy nuclei, 4) deficiencies in the extrapolation of binding energies to super-heavy elements (SHE), and 5) a yet inappropriate trend in fission life-times when going to the heaviest SHE. While the first two points have more a formal bias, the other three points have practical implications and wait for solution.
Structure of a low-lying isomer of BOSi$_2$, as a free-space planar cluster, using the Hartree-Fock method plus second order perturbations  [PDF]
G. Forte,G. G. N. Angilella,N. H. March,R. Pucci
Physics , 2014, DOI: 10.1016/j.cplett.2014.06.020
Abstract: The Hartree-Fock (HF) method, supplemented by low-order Moller-Plesset (MP2) perturbation theory, has been utilized to predict the nuclear geometry, assuming planarity, of a low-lying isomer of the free space cluster BOSi$_2$. The planar structure found at equilibrium geometry is shown to be stable against small amplitude molecular vibrations. Finally, some brief comments are made on the possible relevance of the above free-space cluster geometry to the known B-O defects which limit the improvement of minority carrier lifetime in a form of p-type silicon.
A THEORETICAL ANALYSIS OF THE KOHN-SHAM AND HARTREE-FOCK ORBITALS AND THEIR USE IN THE DETERMINATION OF ELECTRONIC PROPERTIES
Zevallos,Jenny; Toro-Labbé,Alejandro;
Journal of the Chilean Chemical Society , 2003, DOI: 10.4067/S0717-97072003000400007
Abstract: in this work a comparative analysis of the performance of the hartree-fock and kohn-sham orbitals energies to produce reliable electronic properties is evaluated. our results suggest that the negative of hartree-fock and kohn-sham highest occupied orbital define upper and lower limits for the experimental values of the first ionization potential. chemical potential, hardness and polarizabilities of seventeen representative molecules have been evaluated at the hartree-fock and density functional theory levels and a new quasi-analytic model to estimated the energy of the lowest unoccupied molecular orbital emerged from the analysis of these properties
Bogolyubov-Hartree-Fock approach to studying the QCD ground state
Molodtsov, S. V.;Zinovjev, G. M.
High Energy Physics - Phenomenology , 2008, DOI: 10.1103/PhysRevD.80.076001
Abstract: The quark's behaviour while influenced by a strong stochastic gluon field is analyzed. An approximate procedure for calculating the effective Hamiltonian is developed and the corresponding ground state within the Hartree-Fock-Bogolyubov approach is found. The comparative analysis of various Hamiltonian models is given and transition to the chiral limit in the Keldysh model is discussed in detail.
Hartree-Fock-Bogoliubov Calculations of the Rotational Band of the Very Heavy $^{254}$No Nucleus  [PDF]
H. Laftchiev,D. Samsoen,P. Quentin,J. Piperova
Physics , 2000, DOI: 10.1007/s100500170023
Abstract: We report on Hartree-Fock-Bogoliubov (HFB) calculations of the ground-state rotationnal band of the heavy nucleus $^{254}$No recently observed experimentally. The calculated quadrupole deformation is consistent with the experimental value of $\beta=0.27$ and is almost constant over the whole band. We also reproduce fairly well the excitation spectra and moments of inertia of this isotope up to the maximal experimentally observed state of spin 20. The rather high stability of this nucleus against fission is illustrated by the deformation energy curve providing very high fission barriers at zero spin within the HFB and HFB plus Lipkin-Nogami formalisms. The variation of these barriers with increased angular velocities is also studied.
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