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Title: FELIX-2.0: New version of the finite element solver for the time dependent generator coordinate method with the Gaussian overlap approximation

The time-dependent generator coordinate method (TDGCM) is a powerful method to study the large amplitude collective motion of quantum many-body systems such as atomic nuclei. Under the Gaussian Overlap Approximation (GOA), the TDGCM leads to a local, time-dependent Schrödinger equation in a multi-dimensional collective space. In this study, we present the version 2.0 of the code FELIX that solves the collective Schrödinger equation in a finite element basis. This new version features: (i) the ability to solve a generalized TDGCM+GOA equation with a metric term in the collective Hamiltonian, (ii) support for new kinds of finite elements and different types of quadrature to compute the discretized Hamiltonian and overlap matrices, (iii) the possibility to leverage the spectral element scheme, (iv) an explicit Krylov approximation of the time propagator for time integration instead of the implicit Crank–Nicolson method implemented in the first version, (v) an entirely redesigned workflow. We benchmark this release on an analytic problem as well as on realistic two-dimensional calculations of the low-energy fission of 240Pu and 256Fm. Low to moderate numerical precision calculations are most efficiently performed with simplex elements with a degree 2 polynomial basis. Higher precision calculations should instead use the spectral element method withmore » a degree 4 polynomial basis. Finally, we emphasize that in a realistic calculation of fission mass distributions of 240Pu, FELIX-2.0 is about 20 times faster than its previous release (within a numerical precision of a few percents).« less
Authors:
ORCiD logo [1] ;  [2] ;  [2] ;  [3]
  1. Univ. Paris-Sud, Orsay (France). Inst. of Nuclear Physics. IN2P3-CNRS
  2. Alternative Energies and Atomic Energy Commission (CEA), Arpajon (France)
  3. Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States). Nuclear and Chemical Science Division
Publication Date:
Report Number(s):
LLNL-JRNL-735217
Journal ID: ISSN 0010-4655
Grant/Contract Number:
AC52-07NA27344; AC05-00OR22725; AC02-05CH11231
Type:
Accepted Manuscript
Journal Name:
Computer Physics Communications
Additional Journal Information:
Journal Volume: 225; Journal ID: ISSN 0010-4655
Publisher:
Elsevier
Research Org:
Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Univ. Paris-Sud, Orsay (France)
Sponsoring Org:
USDOE Office of Science (SC)
Country of Publication:
United States
Language:
English
Subject:
73 NUCLEAR PHYSICS AND RADIATION PHYSICS; 97 MATHEMATICS AND COMPUTING; FELIX; finite element; spectral element; generator coordinate method; Gaussian overlap approximation; nuclear fission
OSTI Identifier:
1438682

Regnier, D., Dubray, N., Verriere, M., and Schunck, N.. FELIX-2.0: New version of the finite element solver for the time dependent generator coordinate method with the Gaussian overlap approximation. United States: N. p., Web. doi:10.1016/j.cpc.2017.12.007.
Regnier, D., Dubray, N., Verriere, M., & Schunck, N.. FELIX-2.0: New version of the finite element solver for the time dependent generator coordinate method with the Gaussian overlap approximation. United States. doi:10.1016/j.cpc.2017.12.007.
Regnier, D., Dubray, N., Verriere, M., and Schunck, N.. 2017. "FELIX-2.0: New version of the finite element solver for the time dependent generator coordinate method with the Gaussian overlap approximation". United States. doi:10.1016/j.cpc.2017.12.007. https://www.osti.gov/servlets/purl/1438682.
@article{osti_1438682,
title = {FELIX-2.0: New version of the finite element solver for the time dependent generator coordinate method with the Gaussian overlap approximation},
author = {Regnier, D. and Dubray, N. and Verriere, M. and Schunck, N.},
abstractNote = {The time-dependent generator coordinate method (TDGCM) is a powerful method to study the large amplitude collective motion of quantum many-body systems such as atomic nuclei. Under the Gaussian Overlap Approximation (GOA), the TDGCM leads to a local, time-dependent Schrödinger equation in a multi-dimensional collective space. In this study, we present the version 2.0 of the code FELIX that solves the collective Schrödinger equation in a finite element basis. This new version features: (i) the ability to solve a generalized TDGCM+GOA equation with a metric term in the collective Hamiltonian, (ii) support for new kinds of finite elements and different types of quadrature to compute the discretized Hamiltonian and overlap matrices, (iii) the possibility to leverage the spectral element scheme, (iv) an explicit Krylov approximation of the time propagator for time integration instead of the implicit Crank–Nicolson method implemented in the first version, (v) an entirely redesigned workflow. We benchmark this release on an analytic problem as well as on realistic two-dimensional calculations of the low-energy fission of 240Pu and 256Fm. Low to moderate numerical precision calculations are most efficiently performed with simplex elements with a degree 2 polynomial basis. Higher precision calculations should instead use the spectral element method with a degree 4 polynomial basis. Finally, we emphasize that in a realistic calculation of fission mass distributions of 240Pu, FELIX-2.0 is about 20 times faster than its previous release (within a numerical precision of a few percents).},
doi = {10.1016/j.cpc.2017.12.007},
journal = {Computer Physics Communications},
number = ,
volume = 225,
place = {United States},
year = {2017},
month = {12}
}