Axially deformed solution of the Skyrme–Hartree–Fock–Bogolyubov equations using the transformed harmonic oscillator basis (III) hfbtho (v3.00): A new version of the program

Pérez, Rodrigo Navarro; Schunck, N.; Lasseri, Raphaël-David; Zhang, C.; Sarich, Jason

doi:10.1016/j.cpc.2017.06.022

Cited by 85 publications

(84 citation statements)

References 27 publications

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“…Our dft solver was based on the latest version of the hfbtho program [43]. hfbtho solves the hfb equation by expanding the solutions in the harmonic oscillator basis and by using successive diagonalizations of the hfb matrix until convergence (within a numerical tolerance) is achieved.…”

Section: The Hfbtho Solvermentioning

confidence: 99%

“…To help acquire and manage such potentially large amounts of data, we developed on top of the hfbtho solver [43] a layer of software parallelized with MPI, which we call the observable engine. This software uses the output of hfbtho to generate and gather theoretical observable results at each configuration and parameter space point combination contained in the Cartesian product of the n nuc nucleus configurations for a given set of parameter space points.…”

Section: The Observable Enginementioning

confidence: 99%

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Calibration of energy density functionals with deformed nuclei

Schunck

O’Neal²,

Grosskopf

et al. 2020

J. Phys. G: Nucl. Part. Phys.

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Nuclear density functional theory is the prevalent theoretical framework for accurately describing nuclear properties at the scale of the entire chart of nuclides. Given an energy functional and a many-body scheme (e.g., single-or multireference level), the predictive power of the theory depends strongly on how the parameters of the energy functionals have been calibrated with experimental data. Expanded algorithms and computing power have enabled recent optimization protocols to include data in deformed nuclei in order to optimize the coupling constants of the energy functional. The primary motivation of this work is to test the robustness of such protocols with respect to some of the technical and numerical details of the underlying calculations, especially when the calibration explores a large parameter space. To this end, we quantify the effect of these uncertainties on both the optimization and statistical emulation of composite objective functions. We also emphasize that Bayesian calibration can provide better estimates of the theoretical errors used to define objective functions.

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Section: The Hfbtho Solvermentioning

confidence: 99%

Section: The Observable Enginementioning

confidence: 99%

Calibration of energy density functionals with deformed nuclei

Schunck

O’Neal²,

Grosskopf

et al. 2020

J. Phys. G: Nucl. Part. Phys.

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“…We chose (arbitrarily) the nucleus Z = 60 and N = 70 for the tests. We used the code HF-BTHO 3 [32] to solve the HFB equation for this nucleus in a deformed HO basis of 16 shells (oscillator length: b0 = 2.0 fm, β 2 = 0.2). We took the SkM* parametrization of the Skyrme functional, a surface-volume pairing interaction with V 0n = V 0p = −250 MeV and an infinite quasiparticle cutoff.…”

Section: φ ≡mentioning

confidence: 99%

Number of particles in fission fragments

2019

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In current simulations of fission, the number of protons and neutrons in a given fission fragment is almost always obtained by integrating the total density of particles in the sector of space that contains the fragment. Because of the antisymmetry of the many-body wave function of the whole nucleus, this procedure systematically gives non-integer numbers of particles in the fragments. We introduce a novel sampling method to estimate rigorously the probability of finding Z protons and N neutrons in a fission fragment without resorting to projectors, which can sometimes give unwieldy results. When applied on standard Hartree-Fock-Bogoliubov many-body states, we show that our approach reproduces indeed the results of full particle number projection. We then estimate the charge and mass number dispersion of several scission configurations in 240 Pu with and without pairing correlations included. We show that odd-even effects in the charge probability naturally occur within our approach, which could explain the well-known odd-even staggering of charge distributions. Our method is applicable either in static calculations of scission configurations such as, e.g. in the macroscopic-microscopic approach or energy density functional theory, but also in explicitly time-dependent density functional theory simulations of fission.Introduction. The theoretical understanding of nuclear fission, discovered in 1938 by O. Hahn and F. Strassmann, remains a vexing challenge even to this day. The fission of a heavy atomic nucleus presents a number of conceptual as well as practical difficulties. A fissioning nucleus is a particular example of a quantum manybody system of strongly-interacting Fermions, whose interaction is only known approximately. Fission dynamics is explicitly time-dependent and involves open channels (mostly neutrons, but also photons). From a fundamental perspective, the physics of scission, or how an interacting, quantum many-body system splits into two wellseparated, interacting, quantum many-body systems, is very poorly known. Although there is considerable experimental data on fission, most of it has to do with the decay of the fission fragments: the mechanism by which these fragments are formed must be described by theory.Several approaches have been developed over the years to describe the fission process. Since fission times are rather slow compared with single-particle types of excitations [1,2], quasi-static approaches are well justified. Most incarnations of these approaches rely on identifying a few collective variables that drive the fission process, mapping out the potential energy surface in this collective space (which fixes all properties of fission fragments) and computing the probability for the nucleus to be at any point on the surface, e.g. with semi-classical dynamics such as Langevin [3][4][5][6][7][8][9][10][11][12], random walk [13][14][15] or with fully quantum-mechanical dynamics such as the time-dependent generator coordinate method [16][17][18][19]. One major limitation of these approac...

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“…Also, we limited ourselves to nuclei with even numbers of protons and neutrons to avoid the complexities associated with odd-A and odd-odd systems [66][67][68]. To carry out our calculations, we used the DFT code HFBTHOv300 [69], which solves the HFB equations through direct diagonalization in the deformed harmonic oscillator basis. We included constraints on the quadrupole deformation β 2 to account for prolate, oblate, and spherical deformations.…”

Section: Theoretical Approachmentioning

confidence: 99%

α -decay energies of superheavy nuclei: Systematic trends

Olsen

Nazarewicz

2019

Phys. Rev. C

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Background: New superheavy nuclei are often identified through their characteristic α-decay energies, which requires accurate calculations of Qα values. While many Qα predictions are available, little is known about their uncertainties, and this makes it difficult to carry out extrapolations to yet-unknown systems.Purpose: This work aims to analyze several models, compare their predictions to available experimental data, and study their performance for the unobserved α-decay chains of 296 120 and 298 120, which are of current experimental interest. Our quantified results will also serve as a benchmark for future, more sophisticated statistical studies. Methods:We use nuclear superfluid Density Functional Theory (DFT) with several Skyrme energy density functionals (EDFs). To estimate systematic model uncertainties we employ uniform model averaging.Results: We evaluated the Qα values for even-even nuclei from Fm to Z = 120. For well deformed nuclei between Fm and Ds, we find excellent consistency between different model predictions, and a good agreement with experiment. For transitional nuclei beyond Ds, inter-model differences grow, resulting in an appreciable systematic error. In particular, our models underestimate Qα for the heaviest nucleus 294 Og. Conclusions:The robustness of DFT predictions for well deformed superheavy nuclei supports the idea of using experimental Qα values, together with theoretical predictions, as reasonable (Z, A) indicators. Unfortunately, this identification method is not expected to work well in the region of deformed-to-spherical shape transition as one approaches N = 184. The use of Qα values in the identification of new superheavy nuclei will benefit greatly from both progress in developing new spectroscopic-quality EDFs and more sophisticated statistical techniques of uncertainty quantification.

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Axially deformed solution of the Skyrme–Hartree–Fock–Bogolyubov equations using the transformed harmonic oscillator basis (III) hfbtho (v3.00): A new version of the program

Cited by 85 publications

References 27 publications

Calibration of energy density functionals with deformed nuclei

Calibration of energy density functionals with deformed nuclei

Number of particles in fission fragments

α -decay energies of superheavy nuclei: Systematic trends

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