| 1. |
- Si, R., et al.
(författare)
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Breit and QED effects on the 3d9 D3/2 2 →2D5/2 transition energy in Co-like ions
- 2018
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Ingår i: Physical Review A. - 2469-9926. ; 98:1
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Tidskriftsartikel (refereegranskat)abstract
- The multiconfiguration Dirac-Hartree-Fock theory is used to calculate the 3d9D3/22→2D5/2 transition energy for Co-like ions with Z=28-100. We investigate how electron correlation, frequency-independent and -dependent Breit interactions, as well as QED corrections vary along the sequence. The well-understood frequency-independent Breit contribution has the largest contribution for all ions. Among the corrections to this, correlation decreases rapidly with Z, the frequency-dependent Breit contribution is important especially for high-Z ions, and the self-energy contribution to the QED becomes the largest correction already for Z>50. We evaluate and compare results for the Self-energy in three different approximations, (i) the approach implemented in the grasp2k package, (ii) the method based on Welton's concept and (iii) a model operator approach recently developed by Shabaev and coworkers. Through comparison with experimental values, it seems that the third set of results have the best agreement with experiments, but the difference from experiments for high-Z ions, is around 0.03%-0.04%, and therefore our results are outside the error bars of the experiments.
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| 2. |
- Froese Fischer, C, et al.
(författare)
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The Lande g-factor in atomic spectroscopy
- 2004
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Ingår i: Molecular Physics. - : Informa UK Limited. - 1362-3028 .- 0026-8976. ; 102:11-12, s. 1177-1184
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Tidskriftsartikel (refereegranskat)abstract
- The role of the Laude g-factor in atomic spectroscopy is explored through theoretical studies for Ne I and Ne II where some experimental values are available. Extended correlation studies in the Breit-Pauli approximation for spectrum calculations are analysed and compared with experiment and other theory. For Ne II, the multiconfiguration Dirac-Hartree-Fock method was also applied, but correlation was restricted only to the effect of core-polarization on the outer electron.
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| 3. |
- Gustafsson, Stefan, et al.
(författare)
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MCDHF and RCI calculations of energy levels, lifetimes and transition rates for 3l3l ', 3l4l ', and 3s5l states in Ca IX - As XXII and Kr XXV
- 2017
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Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 597:A76
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Tidskriftsartikel (refereegranskat)abstract
- Multiconfiguration Dirac-Hartree-Fock (MCDHF) calculations and relativistic configuration interaction (RCI) calculations were performed for states of the 3l3l 0, 3l4l 0 and 3s5l configurations in the Mg-like ions Ca IX - As XXII and KrXXV. Valence and core-valence electron correlation effects are accounted for through large configuration state function expansions. Calculated excitation energies are in very good agreement with observations for the lowest levels. For higher lying levels observations are often missing and present energies aid line identification in spectra. Lifetimes and transition data are given for all ions. There is an excellent agreement for both lifetimes and transition data with recent multiconfiguration Hartree-Fock Breit Pauli calculations.
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| 4. |
- Jönsson, Per, et al.
(författare)
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Accurate multiconfiguration calculations of energy levels, lifetimes, and transition rates for the silicon isoelectronic sequence : Ti IX - Ge XIX, Sr XXV, Zr XXVII, Mo XXIX
- 2016
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Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 585
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Tidskriftsartikel (refereegranskat)abstract
- Multiconfiguration Dirac-Hartree-Fock (MCDHF) calculations and relativistic configuration interaction (RCI) calculations are performed for states of the 3s23p2, 3s3p3 and 3s23p3d configurations in the Si-like ions Ti IX - Ge XIX, Sr XXV, Zr XXVII and Mo XXIX. Valence and core-valence electron correlation effects are accounted for through large configuration state function expansions. Calculated energy levels are compared with data from other calculations and with experimental data from the reference databases. Lifetime and transition rates along with uncertainty estimations are given for all ions. Energies from the calculations are in excellent agreement with observations and computed wavelength are almost of spectroscopic accuracy, aiding line identification in spectra.
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| 5. |
- 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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| 6. |
- Sturesson, Lennart, et al.
(författare)
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JJGEN: A flexible program for generating lists of j j-coupled configuration state functions
- 2007
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Ingår i: Computer Physics Communications. - : Elsevier BV. - 0010-4655 .- 1879-2944. ; 177:6, s. 539-550
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Tidskriftsartikel (refereegranskat)abstract
- The success of large scale relativistic multiconfiguration Dirac-Hartree-Fock calculations for atomic systems rely on judiciously chosen configuration expansions. Dependent on the atomic system as well as on the studied properties, various correlation effects need to be considered. Based on the active set approach, this program allows the user to generate general lists of j j-coupled configuration state functions to be used as input to the grasp2K multiconfiguration Dirac-Hartree-Fock package [P Jonsson, X. He, C. Froese Fischer, I.P. Grant, Comput. Phys. Comm. (2007), in press].
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| 7. |
- Verdebout, S., et al.
(författare)
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Interaction of Variational Localised Correlation Functions for Atomic Properties of Be I
- 2012
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Ingår i: Journal of Physics, Conference Series. - : Institute of Physics Publishing (IOPP). - 1742-6588 .- 1742-6596. ; 388:15
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- We present some progress associated to the localised correlation function interaction (LCFI) method. In this report, the LCFI method is tested not only for total energy but also for the specific mass shift operator, the hyperfine structure parameters and the transition probabilities. These properties are computed for the three lowest electronic states of the beryllium atom. These calculations illustrate the importance of the contraction effects.
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