| 31. |
- Jönsson, Per, et al.
(författare)
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Multiconfiguration Dirac-Hartree-Fock Calculations with Spectroscopic Accuracy : Applications to Astrophysics
- 2017
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Ingår i: Atoms. - : MDPI. - 2218-2004. ; 5:2
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Forskningsöversikt (refereegranskat)abstract
- Atomic data, such as wavelengths, spectroscopic labels, broadening parameters and transition rates, are necessary for many applications, especially in plasma diagnostics, and for interpreting the spectra of distant astrophysical objects. The experiment with its limited resources is unlikely to ever be able to provide a complete dataset on any atomic system. Instead, the bulk of the data must be calculated. Based on fundamental principles and well-justified approximations, theoretical atomic physics derives and implements algorithms and computational procedures that yield the desired data. We review progress and recent developments in fully-relativistic multiconfiguration Dirac-Hartree-Fock methods and show how large-scale calculations can give transition energies of spectroscopic accuracy, i.e., with an accuracy comparable to the one obtained from observations, as well as transition rates with estimated uncertainties of a few percent for a broad range of ions. Finally, we discuss further developments and challenges.
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| 32. |
- Jönsson, Per, et al.
(författare)
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New version : grasp2K relativistic atomic structure package
- 2013
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Ingår i: Computer Physics Communications. - : Elsevier. - 0010-4655 .- 1879-2944. ; 84:9, s. 2197-2203
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Tidskriftsartikel (refereegranskat)abstract
- A revised version of Grasp2K [P. Jönsson, X. He, C. Froese Fischer, I.P. Grant, Comput. Phys. Commun. 177 (2007) 597] is presented. It supports earlier non-block and block versions of codes as well as a new block version in which the njgraf library module [A. Bar-Shalom, M. Klapisch, Comput. Phys. Commun. 50 (1988) 375] has been replaced by the librang angular package developed by Gaigalas based on the theory of [G. Gaigalas, Z.B. Rudzikas, C. Froese Fischer, J. Phys. B: At. Mol. Phys. 30 (1997) 3747, G. Gaigalas, S. Fritzsche, I.P. Grant, Comput. Phys. Commun. 139 (2001) 263]. Tests have shown that errors encountered by njgraf do not occur with the new angular package. The three versions are denoted v1, v2, and v3, respectively. In addition, in v3, the coefficients of fractional parentage have been extended to j = 9/2, making calculations feasible for the lanthanides and actinides. Changes in v2 include minor improvements. For example, the new version of rci2 may be used to compute quantum electrodynamic (QED) corrections only from selected orbitals. In v3, a new program, jj2lsj, reports the percentage composition of the wave function in LSJ and the program rlevels has been modified to report the configuration state function (CSF) with the largest coefficient of an LSJ expansion. The bioscl2 and bioscl3 application programs have been modified to produce a file of transition data with one record for each transition in the same format as in Atsp2K [C. Froese Fischer, G. Tachiev, G. Gaigalas, M.R. Godefroid, Comput. Phys. Commun. 176 (2007) 559], which identifies each atomic state by the total energy and a label for the CSF with the largest expansion coefficient in LSJ intermediate coupling. All versions of the codes have been adapted for 64-bit computer architecture.
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| 33. |
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| 34. |
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| 35. |
- Jönsson, Per, et al.
(författare)
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Relativistic CI Calculations of Spectroscopic Data for the 2p(6) and 2p(5)3l Configurations in Ne-lika Ions between Mg III and Kr XXVII
- 2011
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Energies, E1, M1, E2, M2 transition rates, oscillator strengths, and lifetimes from relativistic configuration interaction calculations are reported for the states of the 2p6, 2p53s, 2p53p, and 2p53d, configurations in all Ne-like ions between Mg III and Kr XXVII. Core-valence and core-core correlation effects are accounted for through SD-expansions to increasing sets of active orbitals. The Breit interaction and leading QED effects are included as perturbations. The results are compared with experiments and other recent benchmark calculations. In Mg III, Al IV, Si V, P VI, S VII, and Ar IX, for which experimental energies are known to high accuracy, the mean error in the calculated energies is only 0.011%.
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| 36. |
- Jönsson, Per, et al.
(författare)
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Relativistic CI calculations of spectroscopic data for the 2p6 and 2p53l configurations in Ne-like ions between Mg III and Kr XXVII
- 2014
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Ingår i: Atomic Data and Nuclear Data Tables. - : Elsevier. - 0092-640X .- 1090-2090. ; 100:1, s. 1-154
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Tidskriftsartikel (refereegranskat)abstract
- Energies, E1, M1, E2, M2 transition rates, oscillator strengths, and lifetimes from relativistic configuration interaction calculations are reported for the states of the 2p6, 2p53s, 2p53p, and 2p53d, configurations in all Ne-like ions between Mg III and Kr XXVII. Core–valence and core–core correlation effects are accounted for through single and double excitations to increasing sets of active orbitals. The Breit interaction and leading quantum electrodynamic effects are included as perturbations. The results are compared with experiments and other recent benchmark calculations. In Mg III, Al IV, Si V, P VI, S VII, and Ar IX, for which experimental energies are known to high accuracy, the mean error in the calculated energies is only 0.011%.
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| 37. |
- Jönsson, Per, et al.
(författare)
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Spectral properties of Sb IV from MCDHF calculations
- 2012
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Ingår i: Journal of Physics B. - : Bibliopolis, Edizioni di Filosofia e Scienze. - 0953-4075 .- 1361-6455. ; 45:16
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Tidskriftsartikel (refereegranskat)abstract
- We report on extensive relativistic multiconfiguration Dirac–Hartree–Fock (MCDHF) spectrum calculations for Sb IV. Energies, LS-compositions and Landé gJ-factors for 60 odd- and even-parity states are computed along with lifetimes and rates for transitions between these states. Results for the 5s2 1S0–5s5p 3Po0 hyperfine-induced transition are also presented. Valence and core-valence electron correlation effects are accounted for by explicit configuration interaction. The calculated energies agree very well with experiment, but the labelling of some of the odd states is ambiguous due to close degeneracies between the 5p5d, 5s7p and 5p6s configurations. Computed lifetimes of the excited states are compared with values from cascade-corrected beam-foil measurements.
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| 38. |
- Jönsson, Per, et al.
(författare)
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The ATSP2K and GRASP2K Multiconfiguration Atomic Structure Program Packages
- 2013
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Ingår i: Book of abstracts. - : Institute of Modern Physics, Chinese Academy of Sciences.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Synopsis The ATSP2K and GRASP2K program packages for large scale atomic calculations are presented. A number of applications are given to illustrate the potential and restriction of the packages.
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| 39. |
- Jönsson, Per, et al.
(författare)
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The Computational Atomic Structure Group : Code Development and Available Resources
- 2014
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Ingår i: Ninth International Conference on Atomic and Molecular Data and Their Applications: book of abstracts. ; , s. 113-113
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- There is an increasing demand for accurate atomic data due to advancements in experimental techniques and investments in large scale research facilities. In astrophysics the quality and resolution of solar and stellar spectra has so improved that the accuracy of atomic data is frequently a limiting factor in the interpretation. Accurate atomic data are also required in plasma physics and in other emerging areas such as laser spectroscopy on isotope separators, X-ray lithography, and lighting research. The needs include accurate transition energies, fine- and hyperfine structures, mass- and field shifts as well as parameters related to interaction with external magnetic fields. Also there is a constant need for transition rates of different multipolarities between excited states. Data are needed for a wide range of elements and ionization stages. To meet the demands for accurate atomic data the COMPutational Atomic Structure (COMPAS) group has been formed. The group is involved in developing state of the art computer codes for atomic structure calculations in the non-relativistic scheme with relativistic corrections in the Breit-Pauli approximation [1] as well as in the fully relativistic domain. Here we describe new developments of the GRASP2K relativistic atomic structure code [2,3]. We present results for a number of systems and properties to illustrate the potential and restriction of modern computational atomic structure. Among the properties are transition rates, hyperfine- and magnetically induced rates, energy structure, and isotope shifts. We also discuss current code developments and plans for future work. The codes developed by the COMPAS group, along with detailed user manuals, are freely available at http://ddwap.mah.se/tsjoek/compas/ .
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| 40. |
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