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Umar, A. S.; Strayer, M. R.; Cusson, R.Y.; Reinhard, P.‐G.; Bromley, D. A.

doi:10.1103/physrevc.32.172

Cited by 85 publications

(86 citation statements)

References 28 publications

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“…Dipole excitation results in the emission of γ radiation and possibly pre-equilibrium particle emission which in turn provides an important cooling mechanism during the early stages of the fusion reaction. Several transport simulations like semiclassical BoltzmannNordheim-Vlasov [5,30] as well as microscopic calculations [9,24,31,32] have confirmed this scenario.…”

Section: Tdhf Study Of Pre-equilibrium Gdr Excitationmentioning

confidence: 75%

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Dynamic microscopic study of pre-equilibrium giant resonance excitation and fusion in the reactions132Sn+48Ca and
Oberacker
¹
,
Umar
²
,
Maruhn
³

et al. 2012
Phys. Rev. C
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We study pre-equilibrium giant dipole resonance excitation and fusion in the neutron-rich system 132 Sn+ 48 Ca at energies near the Coulomb barrier, and we compare photon yields and total fusion cross sections to those of the stable system 124 Sn+ 40 Ca. The dynamic microscopic calculations are carried out on a three-dimensional lattice using both the Time-Dependent Hartree-Fock method and the Density Constrained TDHF method. We demonstrate that the peak of the GDR excitation spectrum occurs at a substantially lower energy than expected for an equilibrated system, thus reflecting the very large prolate elongation of the dinuclear complex during the early stages of fusion. Our theoretical fusion cross-sections for both systems agree reasonably well with recent data measured at HRIBF.

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Section: Tdhf Study Of Pre-equilibrium Gdr Excitationmentioning

confidence: 75%

“…In this case, collective oscillations of protons against neutrons on the way to fusion might occur, the so-called pre-equilibrium giant dipole resonance (GDR) [5][6][7][8][9]. In fusion reactions, the shape of the preequilibrium di-nuclear complex exhibits a very large prolate deformation as compared to the shape of the equilibrated compound nucleus (see e.g.…”

mentioning

confidence: 99%

Dynamic microscopic study of pre-equilibrium giant resonance excitation and fusion in the reactions132Sn+48Ca and
Oberacker
¹
,
Umar
²
,
Maruhn
³

et al. 2012
Phys. Rev. C
Self Cite

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“…[20,21]. The convergence property is as good if not better than in the traditional CHF calculations with a constraint on a single collective degree of freedom.…”

mentioning

confidence: 71%

“…The density constraint is a novel numerical method that was developed in the mid 1980's [20,21] and was used to provide a microscopic description of the formation of shape resonances in light systems [21]. In this approach the TDHF time-evolution takes place with no restrictions.…”

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confidence: 99%

Heavy-ion interaction potential deduced from density-constrained time-dependent Hartree-Fock calculation

2006

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We present a new method for calculating the heavy-ion interaction potential from a densityconstrained time-dependent Hartree-Fock calculation.PACS numbers: 21.60.Jz,25.60.Pj, The study of internuclear potentials for heavy-ion collisions is of fundamental importance for the formation of superheavy elements and nuclei far from stability. While asymptotically such potentials are determined from Coulomb and centrifugal interactions, the short distance behavior strongly depends on the nuclear surface properties and the readjustments of the combined nuclear system, resulting in potential pockets, which determine the characteristics of the compound nuclear system.Among the various approaches for calculating ion-ion potentials are: 1) Phenomenological models such as the Bass model [1,2], the proximity potential [3,4,5,6], and potentials obtained via the double-folding method [7,8,9,10]. Some of these potentials have been fitted to experimental fusion barrier heights and have been remarkably successful in describing scattering data. 2) Semi-microscopic and full microscopic calculations such as the macroscopic-microscopic method [11,12,13], the asymmetric two-center shell-model [14], constrained Hartree-Fock (CHF) with a constraint on the quadrupole moment or some other definition of the internuclear distance [15,16], and other mean-field based calculations [17,18,19].One common physical assumption used in many of the semi-microscopic calculations is the use of the frozen density or the sudden approximation. As the name suggests, in this approximation the nuclear densities are unchanged during the computation of the ion-ion potential as a function of the internuclear distance. On the other hand, the microscopic calculations follow a minimum energy path and allow for the rearrangement of the nuclear densities as the relevant collective parameter changes. As it was pointed out in Ref. [12], CHF calculations seldom produce the correct saddle-point since the system can follow any one of the minimum potential valleys in the multidimensional potential energy surface. In this paper, we shall call this the static adiabatic approximation since a real adiabatic calculation would involve a fully dynamical calculation, thus also including the effects of dynamical rearrangements.One conclusion that may be reached from the discussion above is that ultimately we would like to have an approach for calculating internuclear potentials which is time-dependent and is unrestricted in the choice of collective variables. In this paper we provide such an approach in which time-dependent Hartree-Fock (TDHF) is used for the nuclear dynamics and the potential energy is calculated by constraining the time-dependent density.The density constraint is a novel numerical method that was developed in the mid 1980's [20,21] and was used to provide a microscopic description of the formation of shape resonances in light systems [21]. In this approach the TDHF time-evolution takes place with no restrictions. At certain times during the evolution the instantan...

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“…[22,23], and in CHFB calculations of refs. [24,25], in which the λ is changed iteratively to satisfy the condition (1) at each step.…”

Section: Introductionmentioning

confidence: 99%

Augmented Lagrangian method for constrained nuclear density functional theory

et al. 2010

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Abstract. The augmented Lagrangiam method (ALM), widely used in quantum chemistry constrained optimization problems, is applied in the context of the nuclear Density Functional Theory (DFT) in the self-consistent constrained Skyrme Hartree-Fock-Bogoliubov (CHFB) variant. The ALM allows precise calculations of multi-dimensional energy surfaces in the space of collective coordinates that are needed to, e.g., determine fission pathways and saddle points; it improves the accuracy of computed derivatives with respect to collective variables that are used to determine collective inertia; and is well adapted to supercomputer applications.

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Time-dependent Hartree-Fock calculations of4He+14

Cited by 85 publications

References 28 publications

Dynamic microscopic study of pre-equilibrium giant resonance excitation and fusion in the reactions132Sn+48Ca and
Oberacker
¹
,
Umar
²
,
Maruhn
³

et al. 2012
Phys. Rev. C
Self Cite

Dynamic microscopic study of pre-equilibrium giant resonance excitation and fusion in the reactions132Sn+48Ca and
Oberacker
¹
,
Umar
²
,
Maruhn
³

et al. 2012
Phys. Rev. C
Self Cite

Heavy-ion interaction potential deduced from density-constrained time-dependent Hartree-Fock calculation

Augmented Lagrangian method for constrained nuclear density functional theory

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Time-dependent Hartree-Fock calculations of4He+14

Cited by 85 publications

References 28 publications

Dynamic microscopic study of pre-equilibrium giant resonance excitation and fusion in the reactions132Sn+48Ca andOberacker1, Umar2, Maruhn3 et al. 2012Phys. Rev. CSelf Cite

Dynamic microscopic study of pre-equilibrium giant resonance excitation and fusion in the reactions132Sn+48Ca andOberacker1, Umar2, Maruhn3 et al. 2012Phys. Rev. CSelf Cite

Heavy-ion interaction potential deduced from density-constrained time-dependent Hartree-Fock calculation

Augmented Lagrangian method for constrained nuclear density functional theory

Contact Info

Product

Resources

About

Dynamic microscopic study of pre-equilibrium giant resonance excitation and fusion in the reactions132Sn+48Ca and
Oberacker
¹
,
Umar
²
,
Maruhn
³

et al. 2012
Phys. Rev. C
Self Cite

Dynamic microscopic study of pre-equilibrium giant resonance excitation and fusion in the reactions132Sn+48Ca and
Oberacker
¹
,
Umar
²
,
Maruhn
³

et al. 2012
Phys. Rev. C
Self Cite