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Title: Isospin-invariant Skyrme energy-density-functional approach with axial symmetry

Abstract

Density functional theory (DFT) is the microscopic tool of choice to describe properties of nuclei over the entire nuclear landscape, with a focus on medium-mass and heavy complex systems. Modern energy density functionals (EDFs) often offer a level of accuracy typical of phenomenological approaches based on parameters locally fitted to the data. It is clear, however, that in order to achieve high quality of predictions to guide spectroscopic studies, current functionals must be improved, especially in the isospin channel. In this respect, experimental studies of short-lived nuclei far from stability offer a unique test of isospin aspects of the many-body theory. In this study, we develop the isospin-invariant Skyrme-EDF method by considering local densities in all possible isospin channels and proton-neutron ($p-n$) mixing terms as mandated by the isospin symmetry. The EDF employed has the most general form that depends quadratically on the isoscalar and isovector densities. We test and benchmark the resulting $p-n$ EDF approach, and study the general properties of the new scheme by means of the cranking in the isospin space. We extend the existing axial DFT solver HFBTHO to the case of isospin-invariant EDF approach with all possible $p-n$ mixing terms. Explicit expressions have been derivedmore » for all the densities and potentials that appear in the isospin representation. In practical tests, we consider the Skyrme EDF SkM* and, as a first application, concentrate on Hartree-Fock aspects of the problem, i.e., pairing has been disregarded. Calculations have been performed for the ($A = 78, T ≃ 11), (A = 40, T ≃ 8$), and ($A = 48, T ≃ 4$) isobaric analog chains. Isospin structure of self-consistent $p-n$ mixed solutions has been investigated with and without the Coulomb interaction, which is the sole source of isospin symmetry breaking in our approach. The extended axial HFBTHO solver has been benchmarked against the symmetry-unrestricted HFODD code for deformed and spherical states. We developed and tested a general isospin-invariant Skyrme-EDF framework. The new approach permits spin-isospin densities that may give rise to hitherto unexplored modes in the excitation spectrum. The new formalism has been tested in the Hartree-Fock limit. A systematic comparison between HFODD and HFBTHO results show a maximum deviation of about 10 keV on the total binding energy for deformed nuclei when the Coulomb term is included. Without this term, the results of both solvers agree down to a ~10 eV level.« less

Authors:
 [1];  [2];  [3];  [4];  [5];  [6]
  1. Univ. of Tennessee, Knoxville, TN (United States). Dept. of Physics and Astronomy; Joint Institute for Heavy-Ion Research, Oak Ridge, TN (United States); Univ. of Kashmir, Srinagar (India). Dept. of Physics
  2. Univ. of Tennessee, Knoxville, TN (United States). Dept. of Physics and Astronomy; Joint Institute for Heavy-Ion Research, Oak Ridge, TN (United States); Univ. of North Carolina, Chapel Hill, NC (United States). Dept. of Physics and Astronomy
  3. Univ. of Tennessee, Knoxville, TN (United States). Dept. of Physics and Astronomy; Univ. of Warsaw, Warsaw (Poland). Inst. of Theoretical Physics, Faculty of Physics; Univ. of Jyväskylä, Jyväskylä (Finland). Dept. of Physics
  4. RIKEN Nishina Center, Wako (Japan); Univ. of Tsukuba, Tsukuba (Japan). Center for Computational Sciences
  5. Univ. of Tennessee, Knoxville, TN (United States). Dept. of Physics and Astronomy; Univ. of Warsaw, Warsaw (Poland). Inst. of Theoretical Physics, Faculty of Physics; Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Physics Division
  6. RIKEN Nishina Center, Wako (Japan)
Publication Date:
Research Org.:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Oak Ridge Leadership Computing Facility (OLCF); Univ. of Tennessee, Knoxville, TN (United States)
Sponsoring Org.:
USDOE Office of Science (SC)
OSTI Identifier:
1565208
Grant/Contract Number:  
FG02-06ER41407; FG02-96ER40963; SC0008499
Resource Type:
Journal Article: Accepted Manuscript
Journal Name:
Physical Review. C, Nuclear Physics
Additional Journal Information:
Journal Volume: 89; Journal Issue: 5; Journal ID: ISSN 0556-2813
Publisher:
American Physical Society (APS)
Country of Publication:
United States
Language:
English
Subject:
73 NUCLEAR PHYSICS AND RADIATION PHYSICS; Physics

Citation Formats

Sheikh, J. A., Hinohara, N., Dobaczewski, J., Nakatsukasa, T., Nazarewicz, W., and Sato, K. Isospin-invariant Skyrme energy-density-functional approach with axial symmetry. United States: N. p., 2014. Web. doi:10.1103/physrevc.89.054317.
Sheikh, J. A., Hinohara, N., Dobaczewski, J., Nakatsukasa, T., Nazarewicz, W., & Sato, K. Isospin-invariant Skyrme energy-density-functional approach with axial symmetry. United States. doi:10.1103/physrevc.89.054317.
Sheikh, J. A., Hinohara, N., Dobaczewski, J., Nakatsukasa, T., Nazarewicz, W., and Sato, K. Mon . "Isospin-invariant Skyrme energy-density-functional approach with axial symmetry". United States. doi:10.1103/physrevc.89.054317. https://www.osti.gov/servlets/purl/1565208.
@article{osti_1565208,
title = {Isospin-invariant Skyrme energy-density-functional approach with axial symmetry},
author = {Sheikh, J. A. and Hinohara, N. and Dobaczewski, J. and Nakatsukasa, T. and Nazarewicz, W. and Sato, K.},
abstractNote = {Density functional theory (DFT) is the microscopic tool of choice to describe properties of nuclei over the entire nuclear landscape, with a focus on medium-mass and heavy complex systems. Modern energy density functionals (EDFs) often offer a level of accuracy typical of phenomenological approaches based on parameters locally fitted to the data. It is clear, however, that in order to achieve high quality of predictions to guide spectroscopic studies, current functionals must be improved, especially in the isospin channel. In this respect, experimental studies of short-lived nuclei far from stability offer a unique test of isospin aspects of the many-body theory. In this study, we develop the isospin-invariant Skyrme-EDF method by considering local densities in all possible isospin channels and proton-neutron ($p-n$) mixing terms as mandated by the isospin symmetry. The EDF employed has the most general form that depends quadratically on the isoscalar and isovector densities. We test and benchmark the resulting $p-n$ EDF approach, and study the general properties of the new scheme by means of the cranking in the isospin space. We extend the existing axial DFT solver HFBTHO to the case of isospin-invariant EDF approach with all possible $p-n$ mixing terms. Explicit expressions have been derived for all the densities and potentials that appear in the isospin representation. In practical tests, we consider the Skyrme EDF SkM* and, as a first application, concentrate on Hartree-Fock aspects of the problem, i.e., pairing has been disregarded. Calculations have been performed for the ($A = 78, T ≃ 11), (A = 40, T ≃ 8$), and ($A = 48, T ≃ 4$) isobaric analog chains. Isospin structure of self-consistent $p-n$ mixed solutions has been investigated with and without the Coulomb interaction, which is the sole source of isospin symmetry breaking in our approach. The extended axial HFBTHO solver has been benchmarked against the symmetry-unrestricted HFODD code for deformed and spherical states. We developed and tested a general isospin-invariant Skyrme-EDF framework. The new approach permits spin-isospin densities that may give rise to hitherto unexplored modes in the excitation spectrum. The new formalism has been tested in the Hartree-Fock limit. A systematic comparison between HFODD and HFBTHO results show a maximum deviation of about 10 keV on the total binding energy for deformed nuclei when the Coulomb term is included. Without this term, the results of both solvers agree down to a ~10 eV level.},
doi = {10.1103/physrevc.89.054317},
journal = {Physical Review. C, Nuclear Physics},
issn = {0556-2813},
number = 5,
volume = 89,
place = {United States},
year = {2014},
month = {5}
}

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Cited by: 12 works
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Figures / Tables:

FIG. 1 FIG. 1: Total HF energy of the $A$ = 78, $T$ ≈ 11 IASs as a function of $θ′$ with (solid line) and without (dashed line) the isospin-symmetry-breaking Coulomb term.

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    Status and future of nuclear matrix elements for neutrinoless double-beta decay: a review
    journal, March 2017


    Status and future of nuclear matrix elements for neutrinoless double-beta decay: a review
    journal, March 2017