Physical Review C

Comparison between a thermal and a time-dependent mean-field description of a two level bosonic model

M. C. Cambiaggio, G.G. Dussel, A. M. Szyferman

Published Oct 1, 1999• 0 citations

Abstract

The thermal mean-field (Hartree-Bose-Bogoliubov) approximation is applied to a simple bosonic model that is related to the phase transition from spherical to deformed nuclei. Similarities and differences with the time-dependent approach are discussed, in particular, the sensitivity of each method for the detection of the phase transition.

DOI: 10.1103/physrevc.60.054308

Related papers

Time-dependent mean field description of a two-level bosonic model

M. C. Cambiaggio, G.G. Dussel, J. A. Ramirez

A time-dependent mean field approximation is applied to a simple bosonic model that is related to the phase transition from spherical to deformed nuclei. It is shown that this approximation is very appropriate for the detection of this phase transition. A method for extracting matrix elements is developed and applied for the two-particle transfer operator in this model.

Physical Review CJul 1, 19913 citations

Comparison between the temperature and the time-dependent Hartree-Fock-Bogoliubov descriptions of the pairing interaction

M. C. Cambiaggio, F. G. Carbone, G.G. Dussel

The thermal and the time-dependent versions of the Hartree-Fock-Bogoliubov approximation are used to describe the effects of the pairing interaction in a simple model. Similarities and differences between the two approaches are discussed. In the one-shell case analytic results are obtained which clearly show that as the degeneracy increases the exact energies tend to the limits provided by the approximate methods. A relation between the quasiparticle occupation probability and the seniority is established. In the two-shell case the time-dependent approach approximates all the families of exact states labeled by the shell seniority and gives information on the two different phase transitions present in the model. The finite-temperature method, instead, only approximates the exact energy for the lowest state of each family.

Physical Review CJan 1, 19941 citation

Two-level bosonic model that simulates the transition from a superconductive condensate to an alpha cluster condensate

P. Curutchet, J. Dukelsky, G.G. Dussel +1 more

A simple bosonic model that has two different phases, one corresponding to a condensate of bosons, a situation that resembles spherical nuclei, and a second one of a condensate of pairs of bosons that corresponds to nuclei where the ground state is a condensate of alphalike clusters, is solved in several different approximate treatments and exactly. Some differences due to the finite number of bosons from the known results for large boson systems are obtained.

Physical Review CNov 1, 19898 citations

Comparative study of the requantization of the time-dependent mean field for the dynamics of nuclear pairing

Fang Ni, Takashi Nakatsukasa

To describe quantal collective phenomena, it is useful to requantize the time-dependent mean-field dynamics. We study the time-dependent Hartree-Fock-Bogoliubov (TDHFB) theory for the two-level pairing Hamiltonian, and compare results of different quantization methods. The one constructing microscopic wave functions, using the TDHFB trajectories fulfilling the Einstein-Brillouin-Keller quantization condition, turns out to be the most accurate. The method is based on the stationary-phase approximation to the path integral. We also examine the performance of the collective model which assumes that the pairing gap parameter is the collective coordinate. The applicability of the collective model is limited for the nuclear pairing with a small number of single-particle levels, because the pairing gap parameter represents only a half of the pairing collective space.

arXiv:1712.02954Physical Review CApr 12, 20183 citations

Hartree-Bose mean-field approximation for the interacting boson model (IBM-3)

J. E. García-Ramos, J. M. Arias, J. Dukelsky +2 more

A Hartree-Bose mean-field approximation for the IBM-3 is presented. A Hartree-Bose transformation from spherical to deformed bosons with charge-dependent parameters is proposed which allows bosonic pair correlations and includes higher angular momentum bosons. The formalism contains previously proposed IBM-2 and IBM-3 intrinsic states as particular limits.

Physical Review CFeb 1, 19983 citations

Mean-field approach to excitations of a trapped Bose-Einstein condensate gas at finite temperatures

M. Tohyama

The monopole and quadrupole oscillations of a Bose-Einstein condensate (BEC) gas trapped in a spherically symmetric potential are calculated using the time-dependent Hartree approximation which enables us to use an orthonormal single-particle basis for the description of both the condensate and noncondensate components. It is found that the monopole mode has a much smaller damping rate than the quadrupole mode. The obtained temperature dependence of the frequency shifts and the damping rates of the collective oscillations are found to be consistent with experimental data obtained for BEC gases in anisotropic trapping potentials. A comparison between the time-dependent Hartree approximation and the time-dependent Hartree-Fock approximation is also made and it is found that there is a rather small difference.

Physical Review AApr 26, 200517 citations