356 research outputs found
Linear response theory in the continuum for deformed nuclei: Green's function vs. time-dependent Hartree-Fock with the absorbing-boundary condition
The continuum random-phase approximation is extended to the one applicable to
deformed nuclei. We propose two different approaches. One is based on the use
of the three dimensional (3D) Green's function and the other is the
small-amplitude TDHF with the absorbing-boundary condition. Both methods are
based on the 3D Cartesian grid representation and applicable to systems without
any symmetry on nuclear shape. The accuracy and identity of these two methods
are examined with the BKN interaction. Using the full Skyrme energy functional
in the small-amplitude TDHF approach, we study the isovector giant dipole
states in the continuum for O-16 and for even-even Be isotopes.Comment: 15 pages, 8 figure
Adiabatic Selfconsistent Collective Coordinate Method for Large Amplitude Collective Motion in Superconducting Nuclei
An adiabatic approximation to the selfconsistent collective coordinate method
is formulated in order to describe large amplitude collective motions in
superconducting nuclei on the basis of the time-dependent
Hartree-Fock-Bogoliubov equations of motion. The basic equations are presented
in a local harmonic form which can be solved in a similar way as the
quasiparticle RPA equations. The formalism guarantees the conservation of
nucleon number expectation values. An extension to the multi-dimensional case
is also discussed
Application of the Adiabatic Selfconsistent-Collective-Coordinate Method to a Solvable Model of Prolate-Oblate Shape Coexistence
The adiabatic selfconsistent collective coordinate method is applied to an
exactly solvable multi-O(4) model which simulates nuclear shape coexistence
phenomena. Collective mass and dynamics of large amplitude collective motions
in this model system are analysed, and it is shown that the method can well
describe the tunneling motions through the barrier between the prolate and
oblate local minima in the collective potential. Emergence of the doublet
pattern is well reproduced.Comment: 25 pages including 9 figure
Removal of Spurious Admixture in a Self-consistent Theory of Adiabatic Large Amplitude Collective Motion
In this article we analyse, for a simple model, the properties of a practical
implementation of a fully self-consistent theory of adiabatic large-amplitude
collective motion using the local harmonic approach. We show how we can deal
with contaminations arising from spurious modes, caused by standard simplifying
approximations. This is done both at zero and finite angular momentum. We
analyse in detail the nature of the collective coordinate in regions where they
cross spurious modes and mixing is largest
Stochastic approach to correlations beyond the mean field with the Skyrme interaction
Large-scale calculation based on the multi-configuration Skyrme density
functional theory is performed for the light N=Z even-even nucleus, 12C.
Stochastic procedures and the imaginary-time evolution are utilized to prepare
many Slater determinants. Each state is projected on eigenstates of parity and
angular momentum. Then, performing the configuration mixing calculation with
the Skyrme Hamiltonian, we obtain low-lying energy-eigenstates and their
explicit wave functions. The generated wave functions are completely free from
any assumption and symmetry restriction. Excitation spectra and transition
probabilities are well reproduced, not only for the ground-state band, but for
negative-parity excited states and the Hoyle state.Comment: 4 pages, 1 figure, Talk at 2nd International Nuclear Physics
Conference "Nuclear Structure and Dynamics", Opatija, Croatia, July 9 - 13,
201
Collective Paths Connecting the Oblate and Prolate Shapes in 68Se and 72Kr Suggested by the Adiabatic Self-Consistent Collective Coordinate Method
By means of the adiabatic self-consistent collective coordinate method and
the pairing-plus-quadrupole interaction, we have obtained the self-consistent
collective path connecting the oblate and prolate local minima in 68Se and 72Kr
for the first time. The self-consistent collective path is found to run
approximately along the valley connecting the oblate and prolate local minima
in the collective potential energy landscape. This result of calculation
clearly indicates the importance of triaxial deformation dynamics in
oblate-prolate shape coexistence phenomena.Comment: 24 pages including 5 figure
Nuclear Excitations Described by Randomly Selected Multiple Slater Determinants
We propose a new stochastic method to describe low-lying excited states of
finite nuclei superposing multiple Slater determinants without assuming
generator coordinates a priori. We examine accuracy of our method by using
simple BKN interaction.Comment: Talk at International Symposium on Correlation Dynamics in Nuclei,
Tokyo, Japan, 31 Jan.-- 4 Feb. 200
Aspects of electron-phonon interactions with strong forward scattering in FeSe Thin Films on SrTiO substrates
Mono- and multilayer FeSe thin films grown on SrTiO and
BiTiO substrates exhibit a greatly enhanced superconductivity over
that found in bulk FeSe. A number of proposals have been advanced for the
mechanism of this enhancement. One possibility is the introduction of a
cross-interface electron-phonon (-) interaction between the FeSe
electrons and oxygen phonons in the substrates that is peaked in the forward
scattering (small ) direction due to the two-dimensional nature of the
interface system. Motivated by this, we explore the consequences of such an
interaction on the superconducting state and electronic structure of a
two-dimensional system using Migdal-Eliashberg theory. This interaction
produces not only deviations from the expectations of conventional
phonon-mediated pairing but also replica structures in the spectral function
and density of states, as probed by angle-resolved photoemission spectroscopy,
scanning tunneling microscopy/spectroscopy, and quasi-particle interference
imaging. We also discuss the applicability of Migdal-Eliashberg theory for a
situation where the \ep interaction is peaked at small momentum transfer and in
the FeSe/STO system
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