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Jönsson, P., Godefroid, M., Gaigalas, G., Ekman, J., Grumer, J., Li, W., . . . Fischer, C. F. (2023). An Introduction to Relativistic Theory as Implemented in GRASP. Atoms, 11(1), Article ID 7.
Open this publication in new window or tab >>An Introduction to Relativistic Theory as Implemented in GRASP
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2023 (English)In: Atoms, E-ISSN 2218-2004, Vol. 11, no 1, article id 7Article in journal (Refereed) Published
Abstract [en]

Computational atomic physics continues to play a crucial role in both increasing the understanding of fundamental physics (e.g., quantum electrodynamics and correlation) and producing atomic data for interpreting observations from large-scale research facilities ranging from fusion reactors to high-power laser systems, space-based telescopes and isotope separators. A number of different computational methods, each with their own strengths and weaknesses, is available to meet these tasks. Here, we review the relativistic multiconfiguration method as it applies to the General Relativistic Atomic Structure Package [grasp2018, C. Froese Fischer, G. Gaigalas, P. Jonsson, J. Bieron, Comput. Phys. Commun. (2018). DOI: 10.1016/j.cpc.2018.10.032]. To illustrate the capacity of the package, examples of calculations of relevance for nuclear physics and astrophysics are presented.

Place, publisher, year, edition, pages
MDPI, 2023
Keywords
ATOMS, GRASP, atomic properties, relativistic atomic structure, multiconfigurational Dirac-Hartree-Fock, finite difference numerical methods, angular integration, configuration interaction, atomic wave function, configuration state function
National Category
Atom and Molecular Physics and Optics
Identifiers
urn:nbn:se:mau:diva-58382 (URN)10.3390/atoms11010007 (DOI)000914435800001 ()2-s2.0-85146498485 (Scopus ID)
Available from: 2023-02-27 Created: 2023-02-27 Last updated: 2023-09-08Bibliographically approved
Bieron, J., Fischer, C. F. & Jönsson, P. (2023). Editorial of the Special Issue "General Relativistic Atomic Structure Program-GRASP". Atoms, 11(6), Article ID 93.
Open this publication in new window or tab >>Editorial of the Special Issue "General Relativistic Atomic Structure Program-GRASP"
2023 (English)In: Atoms, E-ISSN 2218-2004, Vol. 11, no 6, article id 93Article in journal, Editorial material (Other academic) Published
Place, publisher, year, edition, pages
MDPI, 2023
National Category
Atom and Molecular Physics and Optics
Identifiers
urn:nbn:se:mau:diva-61950 (URN)10.3390/atoms11060093 (DOI)001033319000001 ()2-s2.0-85163704308 (Scopus ID)
Available from: 2023-08-17 Created: 2023-08-17 Last updated: 2023-08-17Bibliographically approved
Li, W., Jönsson, P., Amarsi, A. M., Li, M. C. & Grumer, J. (2023). Extended atomic data for oxygen abundance analyses. Astronomy and Astrophysics, 674, Article ID A54.
Open this publication in new window or tab >>Extended atomic data for oxygen abundance analyses
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2023 (English)In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 674, article id A54Article in journal (Refereed) Published
Abstract [en]

As the most abundant element in the universe after hydrogen and helium, oxygen plays a key role in planetary, stellar, and galactic astrophysics. Its abundance is especially influential in terms of stellar structure and evolution, and as the dominant opacity contributor at the base of the Sun's convection zone, it is central to the discussion on the solar modelling problem. However, abundance analyses require complete and reliable sets of atomic data. We present extensive atomic data for O I by using the multiconfiguration Dirac-Hartree-Fock and relativistic configuration interaction methods. We provide the lifetimes and transition probabilities for radiative electric dipole transitions and we compare them with results from previous calculations and available measurements. The accuracy of the computed transition rates is evaluated by the differences between the transition rates in Babushkin and Coulomb gauges, as well as via a cancellation factor analysis. Out of the 989 computed transitions in this work, 205 are assigned to the accuracy classes AA-B, that is, with uncertainties smaller than 10%, following the criteria defined by the Atomic Spectra Database from the National Institute of Standards and Technology. We discuss the influence of the new log(gf) values on the solar oxygen abundance, ultimately advocating for log epsilon(O) = 8.70 +/- 0.04.

Place, publisher, year, edition, pages
EDP Sciences, 2023
Keywords
atomic data, Sun: abundances
National Category
Astronomy, Astrophysics and Cosmology
Identifiers
urn:nbn:se:mau:diva-61959 (URN)10.1051/0004-6361/202245645 (DOI)001000113500006 ()2-s2.0-85162085336 (Scopus ID)
Available from: 2023-08-17 Created: 2023-08-17 Last updated: 2023-08-17Bibliographically approved
Li, M. C., Li, W., Jönsson, P., Amarsi, A. M. & Grumer, J. (2023). Extended MCDHF Calculations of Energy Levels and Transition Data for N I. Astrophysical Journal Supplement Series, 265(1), Article ID 26.
Open this publication in new window or tab >>Extended MCDHF Calculations of Energy Levels and Transition Data for N I
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2023 (English)In: Astrophysical Journal Supplement Series, ISSN 0067-0049, E-ISSN 1538-4365, Vol. 265, no 1, article id 26Article in journal (Refereed) Published
Abstract [en]

Accurate and extensive atomic data are essential for spectroscopic analyses of stellar atmospheres and other astronomical objects. We present energy levels, lifetimes, and transition probabilities for neutral nitrogen, the sixth most abundant element in the cosmos. The calculations employ the fully relativistic multiconfiguration Dirac-Hartree-Fock and relativistic configuration interaction methods, and span the 103 lowest states up to and including 2s(2)2p(2)5s. Our theoretical energies are in excellent agreement with the experimental data, with an average relative difference of 0.07%. In addition, our transition probabilities are in good agreement with available experimental and theoretical data. We further verify the agreement of our data with experimental results via a reanalysis of the solar nitrogen abundance, with the results from the Babushkin and Coulomb gauges consistent to 2% or 0.01 dex. We estimated the uncertainties of the computed transition data based on a statistical analysis of the differences between the transition rates in the Babushkin and Coulomb gauges. Out of the 1701 computed electric dipole transitions in this work, 83 (536) are associated with uncertainties smaller than 5% (10%).

Place, publisher, year, edition, pages
Institute of Physics Publishing (IOPP), 2023
National Category
Atom and Molecular Physics and Optics
Identifiers
urn:nbn:se:mau:diva-59283 (URN)10.3847/1538-4365/acb705 (DOI)000945523200001 ()2-s2.0-85150019214 (Scopus ID)
Available from: 2023-04-20 Created: 2023-04-20 Last updated: 2023-04-20Bibliographically approved
Atalay, B., Jönsson, P. & Brage, T. (2023). Extended relativistic multiconfiguration calculations of energy levels and transition properties in singly ionized tin. Journal of Quantitative Spectroscopy and Radiative Transfer, 294, 108392-108392, Article ID 108392.
Open this publication in new window or tab >>Extended relativistic multiconfiguration calculations of energy levels and transition properties in singly ionized tin
2023 (English)In: Journal of Quantitative Spectroscopy and Radiative Transfer, ISSN 0022-4073, E-ISSN 1879-1352, Vol. 294, p. 108392-108392, article id 108392Article in journal (Refereed) Published
Abstract [en]

Multiconfiguration Dirac-Hartree-Fock (MCDHF) and relativistic configuration interaction (RCI) calculations are performed for 22 states in singly ionized tin (Sn II) belonging to the 5s2ns (n=6,7), 5s2nd (n=5,6), 5s5p2 even parity configurations and the 5s2np (n=5,6,7), 5s24f odd parity configurations. Valence-valence and core-valence correlation effects are taken into account through configuration state function (CSF) expansions. Complete and consistent data sets of level energies, wavelengths, oscillator strengths, lifetimes and transition rates among all these states are given. The results are compared with existing theoretical and experimental results. There is an excellent agreement for calculated excitation energies with experimental data from the NIST database. Lifetimes and transition rates are also in agreement with the results from previous calculations and available measurements for most of the transitions.

Place, publisher, year, edition, pages
Elsevier, 2023
National Category
Atom and Molecular Physics and Optics
Identifiers
urn:nbn:se:mau:diva-56265 (URN)10.1016/j.jqsrt.2022.108392 (DOI)000880814600004 ()2-s2.0-85140611286 (Scopus ID)
Available from: 2022-11-29 Created: 2022-11-29 Last updated: 2024-02-05Bibliographically approved
Li, Y., Gaigalas, G., Li, W., Chen, C. & Jönsson, P. (2023). Fine-Tuning of Atomic Energies in Relativistic Multiconfiguration Calculations. Atoms, 11(4), Article ID 70.
Open this publication in new window or tab >>Fine-Tuning of Atomic Energies in Relativistic Multiconfiguration Calculations
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2023 (English)In: Atoms, E-ISSN 2218-2004, Vol. 11, no 4, article id 70Article in journal (Refereed) Published
Abstract [en]

Ab initio calculations sometimes do not reproduce the experimentally observed energy separations at a high enough accuracy. Fine-tuning of diagonal elements of the Hamiltonian matrix is a process which seeks to ensure that calculated energy separations of the states that mix are in agreement with experiment. The process gives more accurate measures of the mixing than can be obtained in ab initio calculations. Fine-tuning requires the Hamiltonian matrix to be diagonally dominant, which is generally not the case for calculations based on jj-coupled configuration state functions. We show that this problem can be circumvented by a method that transforms the Hamiltonian in jj-coupling to a Hamiltonian in LSJ-coupling for which fine-tuning applies. The fine-tuned matrix is then transformed back to a Hamiltonian in jj-coupling. The implementation of the method into the General Relativistic Atomic Structure Package is described and test runs to validate the program operations are reported. The new method is applied to the computation of the 2s(21)S(0)-2s2p(1,3)P(1) transitions in C III and to the computation of Rydberg transitions in B I, for which the 2s(2)p(22)S(1/2) perturber enters the 2s(2)ns(2)S(1/2) series. Improved convergence patterns and results are found compared with ab initio calculations.

Place, publisher, year, edition, pages
MDPI, 2023
Keywords
fine-tuning, multiconfiguration Dirac-Hartree-Fock, jj-coupling, LSJ-coupling, coupling transformation
National Category
Atom and Molecular Physics and Optics
Identifiers
urn:nbn:se:mau:diva-61070 (URN)10.3390/atoms11040070 (DOI)000981133200001 ()2-s2.0-85153729390 (Scopus ID)
Available from: 2023-06-20 Created: 2023-06-20 Last updated: 2023-06-20Bibliographically approved
Jönsson, P., Gaigalas, G., Fischer, C. F., Bieron, J., Grant, I. P., Brage, T., . . . Li, W. (2023). GRASP Manual for Users. Atoms, 11(4), Article ID 68.
Open this publication in new window or tab >>GRASP Manual for Users
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2023 (English)In: Atoms, E-ISSN 2218-2004, Vol. 11, no 4, article id 68Article in journal (Refereed) Published
Abstract [en]

grasp is a software package in Fortran 95, adapted to run in parallel under MPI, for research in atomic physics. The basic premise is that, given a wave function, any observed atomic property can be computed. Thus, the first step is always to determine a wave function. Different properties challenge the accuracy of the wave function in different ways. This software is distributed under the MIT Licence.

Place, publisher, year, edition, pages
MDPI, 2023
Keywords
GRASP, atomic properties, atomic wave function, multiconfigurational Dirac-Hartree-Fock, configuration interaction
National Category
Atom and Molecular Physics and Optics
Identifiers
urn:nbn:se:mau:diva-61069 (URN)10.3390/atoms11040068 (DOI)000978063800001 ()2-s2.0-85146517458 (Scopus ID)
Available from: 2023-06-20 Created: 2023-06-20 Last updated: 2023-06-20Bibliographically approved
Li, Y., Jönsson, P., Godefroid, M., Gaigalas, G., Bieron, J., Marques, J. P., . . . Chen, C. (2023). Independently Optimized Orbital Sets in GRASP: The Case of Hyperfine Structure in Li I. Atoms, 11(1), Article ID 4.
Open this publication in new window or tab >>Independently Optimized Orbital Sets in GRASP: The Case of Hyperfine Structure in Li I
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2023 (English)In: Atoms, E-ISSN 2218-2004, Vol. 11, no 1, article id 4Article in journal (Refereed) Published
Abstract [en]

In multiconfiguration Dirac-Hartree-Fock (MCDHF) calculations, there is a strong coupling between the localization of the orbital set and the configuration state function (CSF) expansion used to determine it. Furthermore, it is well known that an orbital set resulting from calculations, including CSFs describing core-core correlation and other effects, which aims to lower the weighted energies of a number of targeted states as much as possible, may be inadequate for building CSFs that account for correlation effects that are energetically unimportant but decisive for computed properties, e.g., hyperfine structures or transition rates. This inadequacy can be traced in irregular or oscillating convergence patterns of the computed properties as functions of the increasing orbital set. In order to alleviate the above problems, we propose a procedure in which the orbital set is obtained by merging several separately optimized, and mutually non-orthogonal, orbital sets. This computational strategy preserves the advantages of capturing electron correlation on the total energy through the variational MCDHF method and allows to target efficiently the correlation effects on the considered property. The orbital sets that are merged are successively orthogonalized against each other to retain orthonormality. The merged orbital set is used to build CSFs that efficiently lower the energy and also adequately account for the correlation effects that are important for the property. We apply the procedure to compute the hyperfine structure constants for the 1s(2)2s (2)S1/2 and 1s(2)2p (2Po)(1/2, 3/2) states in Li-7 and show that it leads to considerably improved convergence patterns with respect to the increasing orbital set compared to standard calculations based on a single orbital set, energy optimized in the variational procedure. The perspectives of the new procedure are discussed in a broader context in the summary.

Place, publisher, year, edition, pages
MDPI, 2023
Keywords
variational methods, multiconfiguration Dirac-Hartree-Fock, atomic properties, targeted orbitals, non-orthogonal orbital sets, orthogonalization, convergence
National Category
Physical Sciences
Identifiers
urn:nbn:se:mau:diva-58806 (URN)10.3390/atoms11010004 (DOI)000919471600001 ()2-s2.0-85146506976 (Scopus ID)
Available from: 2023-03-24 Created: 2023-03-24 Last updated: 2024-02-05Bibliographically approved
Li, Y., Li, J., Song, C., Zhang, C., Si, R., Wang, K., . . . Chen, C. (2023). Performance Tests and Improvements on the rmcdhf and rci Programs of GRASP. Atoms, 11(1), Article ID 12.
Open this publication in new window or tab >>Performance Tests and Improvements on the rmcdhf and rci Programs of GRASP
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2023 (English)In: Atoms, E-ISSN 2218-2004, Vol. 11, no 1, article id 12Article in journal (Refereed) Published
Abstract [en]

The latest published version of GRASP (General-purpose Relativistic Atomic Structure Package), i.e., GRASP2018, retains a few suboptimal subroutines/algorithms, which reflect the limited memory and file storage of computers available in the 1980s. Here we show how the efficiency of the relativistic self-consistent-field (SCF) procedure of the multiconfiguration-Dirac-Hartree-Fock (MCDHF) method and the relativistic configuration-interaction (RCI) calculations can be improved significantly. Compared with the original GRASP codes, the present modified version reduces the CPU times by factors of a few tens or more. The MPI performances for all the original and modified codes are carefully analyzed. Except for diagonalization, all computational processes show good MPI scaling.

Place, publisher, year, edition, pages
MDPI, 2023
Keywords
relativistic self-consistent-field (SCF) procedure, relativistic configuration interaction, configuration state function generators, performance tests, code improvements
National Category
Physical Sciences
Identifiers
urn:nbn:se:mau:diva-58383 (URN)10.3390/atoms11010012 (DOI)000914145300001 ()2-s2.0-85146514316 (Scopus ID)
Available from: 2023-02-27 Created: 2023-02-27 Last updated: 2024-02-05Bibliographically approved
Jönsson, P. (2023). Programming, modeling and simulation in Python (1ed.). Lund: Studentlitteratur AB
Open this publication in new window or tab >>Programming, modeling and simulation in Python
2023 (English)Book (Other (popular science, discussion, etc.))
Place, publisher, year, edition, pages
Lund: Studentlitteratur AB, 2023. p. 725 Edition: 1
Keywords
Python, programming, modeling, simulation
National Category
Natural Sciences
Identifiers
urn:nbn:se:mau:diva-64152 (URN)9789144160467 (ISBN)
Available from: 2023-12-07 Created: 2023-12-07 Last updated: 2023-12-08Bibliographically approved
Projects
External interactions and Nuclear Effects in Atoms for Plasma Diagnostics and Fundamental Physics; Malmö UniversityExperimental and computational atomic astrophysics; Malmö University; Publications
Burheim, M., Hartman, H. & Nilsson, H. (2023). Experimental oscillator strengths of Al I lines for near-infrared astrophysical spectroscopy. Astronomy and Astrophysics, 672, Article ID A197.
Organisations
Identifiers
ORCID iD: ORCID iD iconorcid.org/0000-0001-6818-9637

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