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Title: Particle-vibration coupling within covariant density functional theory

Abstract

Covariant density functional theory, which has so far been applied only within the framework of static and time-dependent mean-field theory, is extended to include particle-vibration coupling (PVC) in a consistent way. Starting from a conventional energy functional, we calculate the low-lying collective vibrations in the relativistic random phase approximation (RRPA) and construct an energy-dependent self-energy for the Dyson equation. The resulting Bethe-Salpeter equation in the particle-hole (p-h) channel is solved in the time blocking approximation (TBA). No additional parameters are used, and double counting is avoided by a proper subtraction method. The same energy functional, i.e., the same set of coupling constants, generates the Dirac-Hartree single-particle spectrum, the static part of the residual p-h interaction, and the particle-phonon coupling vertices. Therefore, a fully consistent description of nuclear excited states is developed. This method is applied for an investigation of damping phenomena in the spherical nuclei with closed shells {sup 208}Pb and {sup 132}Sn. Since the phonon coupling terms enrich the RRPA spectrum with a multitude of p-hxphonon components, a noticeable fragmentation of the giant resonances is found, which is in full agreement with experimental data and with results of the semiphenomenological nonrelativistic approach.

Authors:
; ;  [1];  [2];  [3]
  1. Physik-Department der Technischen Universitaet Muenchen, D-85748 Garching (Germany) and Institute of Physics and Power Engineering, RU-249033 Obninsk (Russian Federation)
  2. (Germany)
  3. (Russian Federation)
Publication Date:
OSTI Identifier:
21003455
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physical Review. C, Nuclear Physics; Journal Volume: 75; Journal Issue: 6; Other Information: DOI: 10.1103/PhysRevC.75.064308; (c) 2007 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
73 NUCLEAR PHYSICS AND RADIATION PHYSICS; BETHE-SALPETER EQUATION; COLLECTIVE MODEL; COUPLING; DENSITY FUNCTIONAL METHOD; GIANT RESONANCE; LEAD 208; NUCLEAR FRAGMENTATION; PARTICLES; PHONONS; RANDOM PHASE APPROXIMATION; RELATIVISTIC RANGE; SELF-ENERGY; SHELL MODELS; SPHERICAL CONFIGURATION; TIME DEPENDENCE; TIN 132; VIBRATIONAL STATES

Citation Formats

Litvinova, E., Ring, P., Tselyaev, V., Physik-Department der Technischen Universitaet Muenchen, D-85748 Garching, and Nuclear Physics Department, V.A. Fock Institute of Physics, St. Petersburg State University, RU-198504 St. Petersburg. Particle-vibration coupling within covariant density functional theory. United States: N. p., 2007. Web. doi:10.1103/PHYSREVC.75.064308.
Litvinova, E., Ring, P., Tselyaev, V., Physik-Department der Technischen Universitaet Muenchen, D-85748 Garching, & Nuclear Physics Department, V.A. Fock Institute of Physics, St. Petersburg State University, RU-198504 St. Petersburg. Particle-vibration coupling within covariant density functional theory. United States. doi:10.1103/PHYSREVC.75.064308.
Litvinova, E., Ring, P., Tselyaev, V., Physik-Department der Technischen Universitaet Muenchen, D-85748 Garching, and Nuclear Physics Department, V.A. Fock Institute of Physics, St. Petersburg State University, RU-198504 St. Petersburg. Fri . "Particle-vibration coupling within covariant density functional theory". United States. doi:10.1103/PHYSREVC.75.064308.
@article{osti_21003455,
title = {Particle-vibration coupling within covariant density functional theory},
author = {Litvinova, E. and Ring, P. and Tselyaev, V. and Physik-Department der Technischen Universitaet Muenchen, D-85748 Garching and Nuclear Physics Department, V.A. Fock Institute of Physics, St. Petersburg State University, RU-198504 St. Petersburg},
abstractNote = {Covariant density functional theory, which has so far been applied only within the framework of static and time-dependent mean-field theory, is extended to include particle-vibration coupling (PVC) in a consistent way. Starting from a conventional energy functional, we calculate the low-lying collective vibrations in the relativistic random phase approximation (RRPA) and construct an energy-dependent self-energy for the Dyson equation. The resulting Bethe-Salpeter equation in the particle-hole (p-h) channel is solved in the time blocking approximation (TBA). No additional parameters are used, and double counting is avoided by a proper subtraction method. The same energy functional, i.e., the same set of coupling constants, generates the Dirac-Hartree single-particle spectrum, the static part of the residual p-h interaction, and the particle-phonon coupling vertices. Therefore, a fully consistent description of nuclear excited states is developed. This method is applied for an investigation of damping phenomena in the spherical nuclei with closed shells {sup 208}Pb and {sup 132}Sn. Since the phonon coupling terms enrich the RRPA spectrum with a multitude of p-hxphonon components, a noticeable fragmentation of the giant resonances is found, which is in full agreement with experimental data and with results of the semiphenomenological nonrelativistic approach.},
doi = {10.1103/PHYSREVC.75.064308},
journal = {Physical Review. C, Nuclear Physics},
number = 6,
volume = 75,
place = {United States},
year = {Fri Jun 15 00:00:00 EDT 2007},
month = {Fri Jun 15 00:00:00 EDT 2007}
}
  • A consistent combination of covariant density-functional theory and Landau-Migdal theory of finite fermi systems is presented. Both methods are in principle exact, but Landau-Migdal theory cannot describe ground-state properties and density-functional theory does not take into account the energy dependence of the self-energy and therefore fails to yield proper single-particle spectra as well as the coupling to complex configurations in the width of giant resonances. Starting from an energy functional, phonon energies and their vertices are calculated without any further parameters. They form the basis of particle-vibrational coupling leading to an energy dependence of the self-energy and an induced energy-dependentmore » interaction in the response equation. A proper subtraction of the static phonon-coupling contribution from the induced interaction avoids double counting of this contribution. Applications in doubly magic nuclei and in a chain of superfluid nuclei show excellent agreement with experimental data.« less
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