Collective response of nuclei: Comparison between experiments and extended mean-field calculations

Lacroix, Denis; Ayık, S.; Chomaz, Philippe

doi:10.1103/physrevc.63.064305

Cited by 25 publications

(28 citation statements)

References 70 publications

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“…Inclusion of pairing correlations is possible within the time-dependent Hartree-Fock-Bogolyubov theory [27], but realistic applications in three dimensions are not yet achieved. Extension to theories going beyond the one-body limit such as extended TDHF [26], second RPA [28,29], time-dependent density matrix theory [30][31][32] or stochastic one-body transport theory [33] should be considered for realistic description of giant resonance properties [34].…”

Section: The Time-dependent Hartree-fock Approach a Applicationmentioning

confidence: 99%

Couplings between dipole and quadrupole vibrations in tin isotopes

Simenel¹,

Chomaz²

2009

Phys. Rev. C

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We study the couplings between collective vibrations such as the isovector giant dipole and isoscalar giant quadrupole resonances in tin isotopes in the framework of the time-dependent Hartree-Fock theory with a Skyrme energy density functional. These couplings are a source of anharmonicity in the multiphonon spectrum. In particular, the residual interaction is known to couple the isovector giant dipole resonance with the isoscalar giant quadrupole resonance built on top of it, inducing a nonlinear evolution of the quadrupole moment after a dipole boost. This coupling also affects the dipole motion in a nucleus with a static or dynamical deformation induced by a quadrupole constraint or boost respectively. Three methods associated with these different manifestations of the coupling are proposed to extract the corresponding matrix elements of the residual interaction. Numerical applications of the different methods to 132 Sn are in good agreement with each other. Finally, several tin isotopes are considered to investigate the role of isospin and mass number on this coupling. A simple 1/A dependence of the residual matrix elements is found with no noticeable contribution from the isospin. This result is interpreted within the Goldhaber-Teller model.

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Section: The Time-dependent Hartree-fock Approach a Applicationmentioning

confidence: 99%

Couplings between dipole and quadrupole vibrations in tin isotopes

Simenel¹,

Chomaz²

2009

Phys. Rev. C

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“…We have taken into account only phonons ( j 3 ) with energy smaller than the energy of particle threshold, as well as in the calculations based on the second RPA versions [14][15][16][17][18]. The quantity L(E, E 2p−2h ) is a lorentzian type function,…”

Section: The Semi-microscopic Approachmentioning

confidence: 99%

“…However, in face to the enormous dimensions of the matrices that describe the second RPA these calculations become impracticable, mainly when applied to the heavy nuclei, requiring a long time of numerical computation. To outline these intrinsic numerical difficulties some approximated methods were developed to calculate the widths related with more complex structure than 1p − 1h [14][15][16][17][18][19].…”

Section: Introductionmentioning

confidence: 99%

The spreading width calculation of giant resonances with a semi-microscopic approach

Leite¹,

Teruya²

2006

Braz. J. Phys.

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We have proposed a semi-microscopic approach to calculate the two particles -two holes (2p − 2h) spreading width of giant resonances. Our proposal has been based in a hybrid method that implements the statistical multistep compound theory of Feshbach, Kerman and Koonin (FKK), widely and successful used in nuclear reactions mechanisms, in order to include relevant informations about the microscopic structure obtained by the Random Phase Approximation (RPA) calculations. This method is an approximative calculation to avoid the intrinsic numerical difficulties of those microscopic calculations that incorporate more complex structure than one particle -one hole (1p − 1h) excitations. Unlike the reaction context, the residual interaction was adjusted in RPA calculation to reproduce the lowest energy levels of the studied nuclei. The feasibility and the efficiency of the approach has been tested in giant dipole resonances in 208 Pb and neutron-rich calcium isotopes, 48 Ca and 60 Ca.

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“…This latter is, among the different theories, the only one that has been applied to large amplitude collective motions in the semi-classical limit [12]. Recently, its quantal version has been used to describe small amplitude collective vibrations in nuclei [13]. However the application of a stochastic approach to the quantum many-body dynamics remains an open problem both from a numerical as well as a conceptual point of view [14,15].…”

Section: Introductionmentioning

confidence: 99%

Exact and approximate many-body dynamics with stochastic one-body density matrix evolution

Lacroix

2005

Phys. Rev. C

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We show that the dynamics of interacting fermions can be exactly replaced by a quantum jump theory in the many-body density matrix space. In this theory, jumps occur between densities formed of pairs of Slater determinants, D ab = |Φa Φ b |, where each state evolves according to the Stochastic Schrödinger Equation (SSE) given in ref. [1]. A stochastic Liouville-von Neumann equation is derived as well as the associated Bogolyubov-Born-Green-Kirwood-Yvon (BBGKY) hierarchy. Due to the specific form of the many-body density along the path, the presented theory is equivalent to a stochastic theory in one-body density matrix space, in which each density matrix evolves according to its own mean field augmented by a one-body noise. Guided by the exact reformulation, a stochastic mean field dynamics valid in the weak coupling approximation is proposed. This theory leads to an approximate treatment of two-body effects similar to the extended Time-Dependent Hartree-Fock (Extended TDHF) scheme. In this stochastic mean field dynamics, statistical mixing can be directly considered and jumps occur on a coarse-grained time scale. Accordingly, numerical effort is expected to be significantly reduced for applications.

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Collective response of nuclei: Comparison between experiments and extended mean-field calculations

Cited by 25 publications

References 70 publications

Couplings between dipole and quadrupole vibrations in tin isotopes

Couplings between dipole and quadrupole vibrations in tin isotopes

The spreading width calculation of giant resonances with a semi-microscopic approach

Exact and approximate many-body dynamics with stochastic one-body density matrix evolution

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