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  • 1. Aasa, Sverker
    et al.
    Jönsson, Per
    Malmö högskola, School of Teacher Education (LUT), Nature-Environment-Society (NMS).
    Alfredsson, Karl
    Heath, Carl
    Åresund, Maria
    Alpha version of the game MathX: the search for ancient wisdom2007Report (Other academic)
  • 2. Andersson, Martin
    et al.
    Grumer, Jon
    Ryde, Nils
    Blackwell-Whitehead, Richard
    Hutton, Roger
    Zou, Yaming
    Jönsson, Per
    Malmö högskola, Faculty of Technology and Society (TS).
    Brage, Tomas
    Hyperfine-dependent gf-values of Mn I Lines in the 1.49-1.80 ?m H Band2015In: Astrophysical Journal Supplement Series, ISSN 0067-0049, E-ISSN 1538-4365, Vol. 216, no 1, article id 2Article in journal (Refereed)
    Abstract [en]

    The three Mn i lines at 17325, 17339, and 17349Å are among the 25 strongest lines (log(gf ) > 0.5) in the H band. They are all heavily broadened due to hyperfine structure, and the profiles of these lines have so far not been understood. Earlier studies of these lines even suggested that they were blended. In this work, the profiles of these three infrared (IR) lines have been studied theoretically and compared to experimental spectra to assist in the complete understanding of the solar spectrum in the IR. It is shown that the structure of these lines cannot be described in the conventional way using the diagonal A and B hyperfine interaction constants. The off-diagonal hyperfine interaction not only has a large impact on the energies of the hyperfine levels, but also introduces a large intensity redistribution among the hyperfine lines, changing the line profiles dramatically. By performing large-scale calculations of the diagonal and off-diagonal hyperfine interaction and the gf -values between the upper and lower hyperfine levels and using a semi-empirical fitting procedure, we achieved agreement between our synthetic and experimental spectra. Furthermore, we compare our results with observations of stellar spectra. The spectra of the Sun and the K1.5 III red giant star Arcturus were modeled in the relevant region, 1.73–1.74 μm, using our theoretically predicted gf -values and energies for each individual hyperfine line. Satisfactory fits were obtained and clear improvements were found using our new data compared with the old available Mn i data. A complete list of energies and gf -values for all the 3d54s(7S)4d e6D – 3d54s(7S)4f w6F hyperfine lines are available as supporting material, whereas only the stronger lines are presented and discussed in detail in this paper.

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  • 3. Andersson, Martin
    et al.
    Jönsson, Per
    Malmö högskola, School of Teacher Education (LUT), Nature-Environment-Society (NMS).
    Sabel, Hans
    Hyperfine induced interference effects in the 4s4d 3D2–4s4f 3F2,3 transitions in Ga II2006In: Journal of Physics B: Atomic, Molecular and Optical Physics, ISSN 0953-4075, E-ISSN 1361-6455, Vol. 39, no 20, p. 4239-4247Article in journal (Refereed)
    Abstract [en]

    We report relativistic multiconfiguration Dirac–Hartree–Fock calculations of transitions between the hyperfine levels of 4s4f 3F2,3 and 4s4d 3D2 in Ga II. The capacity of two newly developed programs connected to the graspVU package for generating synthetic spectra is explored. The obtained theoretical spectra are compared to Fourier transform spectra and good agreement is found. The importance of hyperfine induced interference effects for the 4s4d 3D2–4s4f 3F2 transitions is pointed out, and the gf values for all the hyperfine transitions are given.

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  • 4. Aourir, Nouria
    et al.
    Nemouchi, Messaoud
    Godefroid, Michel
    Jönsson, Per
    Malmö University, Faculty of Technology and Society (TS), Department of Materials Science and Applied Mathematics (MTM).
    Theoretical hyperfine structures of F-19 I and O-17 I2018In: Physical Review A: covering atomic, molecular, and optical physics and quantum information, ISSN 2469-9926, E-ISSN 2469-9934, Vol. 97, no 3, article id 032506Article in journal (Refereed)
    Abstract [en]

    Multiconfiguration Hartree-Fock (MCHF) and multiconfiguration Dirac-Hartree-Fock (MCDHF) calculations are performed for the 2p(5) P-2 degrees, 2p(4)(P-3)3s P-4, 2p(4)(P-3)3s P-2, and 2p(4)(P-3)3 p S-4 degrees states of F-19 I to determine their hyperfine constants. Several computing strategies are considered to investigate electron correlation and relativistic effects. High-order correlation contributions are included in MCHF calculations based on single and double multireference expansions. The largest components of the single reference MCHF wave functions are selected to define the multireference (MR) sets. In this scheme, relativistic corrections are evaluated in the Breit-Pauli approximation. A similar strategy is used for the calculation of MCDHF relativistic wave functions and hyperfine parameters. While correlation and relativistic corrections are found to be rather small for the ground state, we highlight large relativistic effects on the hyperfine constant A(3/2) of 2p(4)(P-3)3 p(4)S(degrees) and, to a lesser extent, on A(1/2) of 2p(4)(P-3)3s P-4. As expected for such a light system, electron correlation effects dominate over relativity in the calculation of the hyperfine interaction of all other levels considered. We also revisit the hyperfine constants of 2p(3)((4)(S))3s S-5 degrees and 2p(3)(S-4)3 p P-5 in O-17 using similar strategies. The results are found to be in excellent agreement with experiment.

  • 5. Atalay, B.
    et al.
    Brage, T.
    Jönsson, Per
    Malmö University, Faculty of Technology and Society (TS), Department of Materials Science and Applied Mathematics (MTM).
    Hartman, Henrik
    Malmö University, Faculty of Technology and Society (TS), Department of Materials Science and Applied Mathematics (MTM).
    MCDHF and RCI calculations of energy levels, lifetimes, and transition rates in Si III and Si IV2019In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, ISSN 0004-6361, Vol. 631, article id A29Article in journal (Refereed)
    Abstract [en]

    We present extensive multiconfiguration Dirac-Hartree-Fock and relativistic configuration interaction calculations including 106 states in doubly ionized silicon (Si III) and 45 states in triply ionized silicon (Si IV), which are important for astrophysical determination of plasma properties in different objects. These calculations represents an important extension and improvement of earlier calculations especially for Si III. The calculations are in good agreement with available experiments for excitation energies, transition properties, and lifetimes. Important deviations from the NIST-database for a selection of perturbed Rydberg series are discussed in detail.

  • 6.
    Atalay, B.
    et al.
    Division of Mathematical Physics, Department of Physics, Lund University, LundSE-22100, Sweden; Department of Physics, Çanakkale Onsekiz Mart University, Çanakkale17100, Turkey.
    Jönsson, P.
    Malmö University, Faculty of Technology and Society (TS), Department of Materials Science and Applied Mathematics (MTM).
    Brage, T.
    Division of Mathematical Physics, Department of Physics, Lund University, LundSE-22100, Sweden.
    Extended relativistic multiconfiguration calculations of energy levels and transition properties in singly ionized tin2023In: 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)
    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.

  • 7. Bengtsson, Peter
    et al.
    Ekman, Jörgen
    Malmö högskola, School of Technology (TS).
    Gustafsson, Stefan
    Malmö högskola, School of Technology (TS).
    Jönsson, Per
    Malmö högskola, School of Technology (TS).
    Karlsson, Lennart
    Malmö högskola, School of Technology (TS).
    Gaigalas, Gediminas
    Energy structure and transition rates in the Ne-like sequence from relativistic CI calculations2012In: Europhysics Conference Abstracts;36C, European Physical Society , 2012, p. 128-128Conference paper (Other academic)
    Abstract [en]

    Atomic data are important in astrophysical applications and transition rates can be used in the determination of element abundances and plasma diagnostics. To provide for the extensive data needs a number of general computer codes such as SUPERSTRUCTURE, CIV3, and ATSP2K have been developed. As an alternative to these codes, which all rely on the Breit-Pauli approximation, the fully relativistic GRASP2K code can be used. GRASP2K is based on the multiconfiguration Dirac-Hartree-Fock method and implements a bi-orthogonal transformation method that permits initial and final states in a transition array to be optimized separately, which, in many cases, leads to more accurate values of the resulting rates. The GRASP2K package also contains modules to compute diagonal and off-diagonal hyperfine interaction constants, isotope shifts, Land´e gJ factors, and splittings of magnetic sub-state in intermediate and strong magnetic fields. In this work, GRASP2K has been applied to provide highly accurate spectroscopic data for ions in the Ne-like sequence between Mg III and Kr XXVII. Valence, core-valence, and core-core correlation effects were accounted for through SD-MR expansions to increasing sets of active orbitals. 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%. For ions with no available experimental energy levels the calculated values should be most valuable in various applications. The high accuracy of the calculated energies makes it possible, in some cases, to to point out experimental values that are in error. Babushkin (length) and Coulomb (velocity) forms of transition rates are computed and agree to within a few percent for the majority of the allowed transitions. Computed lifetimes for states belonging to the 2p33s and 2p53d configurations are in good agreement with values from beam-foil measurements as well as from accurate MCHF Breit-Pauli calculations.

  • 8. Bieron, Jacek
    et al.
    Brage, Tomas
    Froese Fischer, Charlotte
    Gaigalas, Gediminas
    Godefroid, Michel
    Jönsson, Per
    Malmö högskola, School of Technology (TS).
    Computational Atomic Structure2012In: Program and Abstracts: Eighth International Conference on Atomic and Molecular Data and Their Applications: ICAMDATA 8, 2012, p. 56-56Conference paper (Other academic)
    Abstract [en]

    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, isotope shifts as well as parameters related to interaction with external magnetic fields. Also there is a constant need for transition rates 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 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 computational atomic structure. Among the properties are hyperfine structures and hyperfine quenched rates, Zeeman splittings in intermediate fields, isotope shifts and transition rates [4]. We also discuss plans for future code developments.

  • 9. Bieron, Jacek
    et al.
    Filippin, Livio
    Gaigalas, Gediminas
    Godefroid, Michel
    Jönsson, Per
    Malmö University, Faculty of Technology and Society (TS), Department of Materials Science and Applied Mathematics (MTM).
    Pyykko, Pekka
    Ab initio calculations of the hyperfine structure of zinc and evaluation of the nuclear quadrupole moment Q(Zn-67)2018In: Physical Review A: covering atomic, molecular, and optical physics and quantum information, ISSN 2469-9926, E-ISSN 2469-9934, Vol. 97, no 6Article in journal (Refereed)
    Abstract [en]

    The relativistic multiconfiguration Dirac-Hartree-Fock and the nonrelativistic multiconfiguration Hartree-Fock methods have been employed to calculate the magnetic dipole and electric quadrupole hyperfine structure constants of zinc. The calculated electric field gradients for the 4s4p P-3(1)degrees and 4s4p P-3(2)degrees states, together with experimental values of the electric quadrupole hyperfine structure constants, made it possible to extract a nuclear electric quadrupole moment Q((67) Zn) = 0.122(10) b. The error bar was evaluated in a quasistatistical approach-the calculations were carried out with 11 different methods, and then the error bar was estimated from the differences between the results obtained with those methods.

  • 10.
    Bieron, Jacek
    et al.
    Uniwersytet Jagiellonski, Inst Fizyki Teoret, PL-30348 Krakow, Poland..
    Fischer, Charlotte Froese
    Univ British Columbia, Dept Comp Sci, Vancouver, BC V6T 1Z4, Canada..
    Jönsson, Per
    Malmö University, Faculty of Technology and Society (TS), Department of Materials Science and Applied Mathematics (MTM).
    Editorial of the Special Issue "General Relativistic Atomic Structure Program-GRASP"2023In: Atoms, E-ISSN 2218-2004, Vol. 11, no 6, article id 93Article in journal (Other academic)
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  • 11. Bieron, Jacek
    et al.
    Froese Fischer, Charlotte
    Fritzsche, Stephan
    Gaigalas, Gediminas
    Grant, Ian
    Indelicato, Paul
    Jönsson, Per
    Malmö högskola, Faculty of Technology and Society (TS).
    Pyykkö, Pekka
    Ab initio MCDHF calculations of electron-nucleus interactions2015In: Physica Scripta, ISSN 0031-8949, E-ISSN 1402-4896, Vol. 90, no 5, article id 054011Article in journal (Refereed)
    Abstract [en]

    We present recent advances in the development of atomic ab initio multiconfiguration Dirac– Hartree–Fock theory, implemented in the GRASP relativistic atomic structure code. For neutral atoms, the deviations of properties calculated within the Dirac–Hartree–Fock (DHF) method (based on independent particle model of an atomic cloud) are usually dominated by electron correlation effects, i.e. the non-central interactions of individual electrons. We present the recent advances in accurate calculations of electron correlation effects in small, medium, and heavy neutral atoms. We describe methods of systematic development of multiconfiguration expansions leading to systematic, controlled improvement of the accuracy of the ab initio calculations. These methods originate from the concept of the complete active space (CAS) model within the DHF theory, which, at least in principle, permits fully relativistic calculations with full account of electron correlation effects. The calculations within the CAS model on currently available computer systems are feasible only for very light systems. For heavier atoms or ions with more than a few electrons, restrictions have to be imposed on the multiconfiguration expansions. We present methods and tools, which are designed to extend the numerical calculations in a controlled manner, where multiconfiguration expansions account for all leading electron correlation effects. We show examples of applications of the GRASP code to calculations of hyperfine structure constants, but the code may be used for calculations of arbitrary bound-state atomic properties. In recent years it has been applied to calculations of atomic and ionic spectra (transition energies and rates), to determinations of nuclear electromagnetic moments, as well as to calculations related to interactions of bound electrons with nuclear electromagnetic moments leading to violations of discrete symmetries.

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  • 12. Bieron, Jacek
    et al.
    Froese Fischer, Charlotte
    Indelicato, Paul
    Jönsson, Per
    Malmö högskola, School of Teacher Education (LUT), Nature-Environment-Society (NMS).
    Pyykkö, Pekka
    Complete Active Space multiconfiguration Dirac-Hartree-Fock calculations of hyperfine structure constants2009Conference paper (Other academic)
  • 13. Bieron, Jacek
    et al.
    Froese Fischer, Charlotte
    Indelicato, Paul
    Jönsson, Per
    Malmö högskola, School of Teacher Education (LUT), Nature-Environment-Society (NMS).
    Pyykkö, Pekka
    Complete-active-space multiconfiguration Dirac-Hartree-Fock calculations of hyperfine-structure constants of the gold atom2009In: Physical Review A. Atomic, Molecular, and Optical Physics, ISSN 1050-2947, E-ISSN 1094-1622, Vol. 79, no 5, article id 052502Article in journal (Refereed)
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  • 14. Bieron, Jacek
    et al.
    Froese Fischer, Charlotte
    Jönsson, Per
    Malmö högskola, School of Teacher Education (LUT), Nature-Environment-Society (NMS).
    Pykköö, Pekka
    Comment on the magnetic dipole hyperfine interaction in the gold atom ground state2008In: Journal of Physics B : Atomic, Molecular and Optical Physics, Vol. 41, no 11, article id 115002Article in journal (Refereed)
    Abstract [en]

    The multiconfiguration Dirac–Hartree–Fock (MCDHF) model has been employed to calculate the magnetic dipole hyperfine constant A of the 5d106s 2S1/2 ground state of atomic gold. Electron correlation effects contribute more than 20% to the total value of A. We investigated the effects of single, double, and a subset of triple substitutions. The calculations reveal strong cancellations between one-, two- and three-particle correlation effects. It is demonstrated that in the case of the ground state of atomic gold the three-particle effects are comparable in size to the one- and two-particle ones.

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  • 15. Bieron, Jacek
    et al.
    Gaigalas, Gediminas
    Gaidamauskas, Erikas
    Fritzsche, Stephan
    Indelicato, Paul
    Jönsson, Per
    Malmö högskola, School of Teacher Education (LUT), Nature-Environment-Society (NMS).
    Multiconfiguration Dirac-Hartree-Fock calculations of the electric dipole moment of radium induced by the nuclear Schiff moment2009In: Physical Review A. Atomic, Molecular, and Optical Physics, ISSN 1050-2947, E-ISSN 1094-1622, Vol. 80, no 1, article id 012513Article in journal (Refereed)
    Abstract [en]

    The multiconfiguration Dirac-Hartree-Fock theory has been employed to calculate the electric dipole moment of the 7s6d 3D2 state of radium induced by the nuclear Schiff moment. The results are dominated by valence and core-valence electron correlation effects. We show that the correlation effects can be evaluated in a converged series of multiconfiguration expansions.

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  • 16.
    Boualili, Fatima Zahra
    et al.
    USTHB, Lab Elect Quant, Fac Phys, BP 32, Algiers, Algeria..
    Nemouchi, Messaoud
    USTHB, Lab Elect Quant, Fac Phys, BP 32, Algiers, Algeria..
    Godefroid, Michel
    Univ Libre Bruxelles, Spect Quantum Chem & Atmospher Remote Sensing, CP 160-09, B-1050 Brussels, Belgium..
    Jönsson, Per
    Malmö University, Faculty of Technology and Society (TS), Department of Materials Science and Applied Mathematics (MTM).
    Weak correlation and strong relativistic effects on the hyperfine interaction in fluorine2021In: Physical Review A: covering atomic, molecular, and optical physics and quantum information, ISSN 2469-9926, E-ISSN 2469-9934, Vol. 104, no 6, article id 062813Article in journal (Refereed)
    Abstract [en]

    In previous work devoted to ab initio calculations of hyperfine-structure constants in nitrogen and fluorine atoms, we observed sizable relativistic effects, a priori unexpected for such light systems, that can even largely dominate over electron correlation. We observed that the atomic wave functions calculated in the Breit-Pauli approximation describe adequately the relevant atomic levels and hyperfine structures, even in cases for which a small relativistic LS-term mixing becomes crucial. In the present work we identify levels belonging to the spectroscopic terms 2p(4)(P-3)3d(2,4)(P, D, F) of the fluorine atom, for which correlation effects on the hyperfine structures are small, but relativistic LS-term admixtures are decisive to correctly reproduce the experimental values. The Breit-Pauli analysis of the hyperfine matrix elements nails cases with large cancellation, either between LS pairs for individual hyperfine operators or between the orbital and the spin dipole contributions. Multiconfiguration Dirac-Hartree-Fock calculations are performed to support the Breit-Pauli analysis.

  • 17.
    Cai, Zhanzhang
    et al.
    Lund University.
    Junttila, Sofia
    Lund University.
    Holst, Jutta
    Lund University.
    Jin, Hongxiao
    Lund University; Technical University of Denmark.
    Ardo, Jonas
    Lund University.
    Ibrom, Andreas
    Technical University of Denmark.
    Peichl, Matthias
    Swedish University of Agricultural Sciences, Umeå.
    Molder, Meelis
    Lund University.
    Jönsson, Per
    Malmö University, Faculty of Technology and Society (TS), Department of Materials Science and Applied Mathematics (MTM).
    Rinne, Janne
    Lund University.
    Karamihalaki, Maria
    Lund University.
    Eklundh, Lars
    Lund University.
    Modelling Daily Gross Primary Productivity with Sentinel-2 Data in the Nordic Region-Comparison with Data from MODIS2021In: Remote Sensing, E-ISSN 2072-4292, Vol. 13, no 3, article id 469Article in journal (Refereed)
    Abstract [en]

    The high-resolution Sentinel-2 data potentially enable the estimation of gross primary productivity (GPP) at finer spatial resolution by better capturing the spatial variation in a heterogeneous landscapes. This study investigates the potential of 10 m resolution reflectance from the Sentinel-2 Multispectral Instrument to improve the accuracy of GPP estimation across Nordic vegetation types, compared with the 250 m and 500 m resolution reflectance from the Moderate Resolution Imaging Spectroradiometer (MODIS). We applied linear regression models with inputs of two-band enhanced vegetation index (EVI2) derived from Sentinel-2 and MODIS reflectance, respectively, together with various environmental drivers to estimate daily GPP at eight Nordic eddy covariance (EC) flux tower sites. Compared with the GPP from EC measurements, the accuracies of modelled GPP were generally high (R-2 = 0.84 for Sentinel-2; R-2 = 0.83 for MODIS), and the differences between Sentinel-2 and MODIS were minimal. This demonstrates the general consistency in GPP estimates based on the two satellite sensor systems at the Nordic regional scale. On the other hand, the model accuracy did not improve by using the higher spatial-resolution Sentinel-2 data. More analyses of different model formulations, more tests of remotely sensed indices and biophysical parameters, and analyses across a wider range of geographical locations and times will be required to achieve improved GPP estimations from Sentinel-2 satellite data.

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  • 18. Carette, Thomas
    et al.
    Jiguang, Li
    Cedric, Naze
    Fritzsche, Stephan
    Jönsson, Per
    Malmö högskola, School of Technology (TS).
    Godefroid, Michel
    Electronic factors for isotope shifts2013Conference paper (Other academic)
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  • 19. Carette, Thomas
    et al.
    Li, Jiguang
    Naze, Cedric
    Fritzsche, Stephan
    Jönsson, Per
    Malmö högskola, School of Technology (TS).
    Godefroid, Michel
    Electronic factors for isotope shifts2013In: Book of abstracts, Institute of Modern Physics, Chinese Academy of Sciences , 2013, article id 17731Conference paper (Other academic)
    Abstract [en]

    Synopsis Progresses have been made in the ab initio calculation of the electronic factors contributing to the mass and eld isotope shifts of atomic spectral lines. We will illustrate these progresses and underline the current limitations.

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  • 20. Carette, Thomas
    et al.
    Nemouchi, Messaoud
    Godefroid, Michel R
    Jönsson, Per
    Malmö högskola, School of Teacher Education (LUT), Nature-Environment-Society (NMS).
    Hyperfine structure of near-infrared transitions in neutral nitrogen revisited2009Conference paper (Other academic)
  • 21. Carette, Thomas
    et al.
    Nemouchi, Messaoud
    Jönsson, Per
    Malmö högskola, School of Technology (TS).
    Godefroid, Michel
    Hyperfine structure of low-lying states of 14;15N (Cairns)2010In: Book of abstracts: Monday posters 3, 2010, p. 238-238Conference paper (Other academic)
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  • 22. Carette, Thomas
    et al.
    Nemouchi, Messaoud
    Jönsson, Per
    Malmö högskola, School of Technology (TS).
    Godefroid, Michel
    Hyperfine structure of low-lying states of 14;15N (Salamanca)2010Conference paper (Other academic)
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  • 23. Carette, Thomas
    et al.
    Nemouchi, Messaoud
    Jönsson, Per
    Malmö högskola, School of Technology (TS).
    Godefroid, Michel
    Hyperfine structure of low-lying states of 14;15N (Vilnius)2010In: Book of Abstracts, 2010, p. 90-90, article id B-11Conference paper (Other academic)
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  • 24. Carette, Thomas
    et al.
    Nemouchi, Messaoud
    Jönsson, Per
    Malmö högskola, School of Technology (TS).
    Godefroid, Michel
    Saturation spectra of low lying states of Nitrogen: reconciling experiment with theory2010In: European Physical Journal D: Atomic, Molecular and Optical Physics, ISSN 1434-6060, E-ISSN 1434-6079, Vol. 60, no 2, p. 231-242Article in journal (Refereed)
    Abstract [en]

    The hyperfine constants of the levels 2p2(3P)3s 4PJ, 2p2(3P)3p 4Po J and 2p2(3P)3p 4Do J, deduced by Jennerich et al. [Eur. Phys. J. D 40, 81 (2006)] from the observed hyperfine structures of the transitions 2p2(3P)3s 4PJ → 2p2(3P)3p 4Po J and 2p2(3P)3s 4PJ → 2p2(3P)3p 4Do J recorded by saturation spectroscopy in the near-infrared, strongly disagree with the ab initio values of Jönsson et al. [J. Phys. B: At. Mol. Opt. Phys. 43, 115006 (2010)]. We propose a new interpretation of the recorded weak spectral lines. If the latter are indeed reinterpreted as crossover signals, a new set of experimental hyperfine constants is deduced, in very good agreement with the ab initio predictions.

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  • 25. Chung, Hyun-Kyung
    et al.
    Jönsson, Per
    Malmö högskola, School of Technology (TS).
    Kramida, Alexander
    Notes on critical assessment of theoretical calculations of atomic structure and transition probabilities2013In: Atoms, E-ISSN 2218-2004, Vol. 1, no 3, p. 14-15Article in journal (Refereed)
    Abstract [en]

    Atomic structure and transition probabilities are fundamental physical data required in many fields of science and technology. Atomic physics codes are freely available to other community users to generate atomic data for their interest, but the quality of these data is rarely verified. This special issue addresses estimation of uncertainties in atomic structure and transition probability calculations, and discusses methods and strategies to assess and ensure the quality of theoretical atomic data.

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  • 26. Eklundh, Lars
    et al.
    Ardö, Jonas
    Jönsson, Per
    Malmö högskola, School of Technology (TS).
    Sjöström, Martin
    High resolution mapping of vegetation dynamics from Sentinel-22012Conference paper (Other academic)
    Abstract [en]

    The aim of this work is to develop and test a method for generation of information on vegetation dynamics from high-spatial resolution data, such as Sentinel-2. In order to accomplish this, Sentinel-2 data were simulated from existing SPOT HRG and HRVIR scenes over Sweden. We used TIMESAT, a well-tested computer package for generating smooth seasonal profiles and generation of seasonality parameters, like start and end, length, amplitude, integrated values, seasonal maximum, derivatives, etc. The processing works on a pixel-by-pixel basis and is resistant to clouds and noise. Data gaps are handled, and quality information can be included to increase the fidelity of the fits. The pilot study demonstrated that TIMESAT was successful in fitting smooth model functions to the data, and generating seasonality parameters for the test area at 10 x 10 m resolution. We conclude that TIMESAT will be useful for generating vegetation dynamics data from high-spatial resolution data such as Sentinel-2. The smooth seasonal profiles will be extremely useful for driving high-resolution biophysical vegetation models, and the seasonality parameters will be excellent for change detection, and for studying trends in vegetation productivity and seasonality.

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  • 27. Eklundh, Lars
    et al.
    Jönsson, Per
    Malmö högskola, School of Technology (TS).
    Seasonality Extraction from Time-Series of Satellite Sensor Data2003In: Frontiers of Remote Sensing Information Processing, edited by C.H. Chen, World Scientific Publishing , 2003, p. 485-501Chapter in book (Other academic)
  • 28. Eklundh, Lars
    et al.
    Jönsson, Per
    Malmö högskola, Faculty of Technology and Society (TS).
    TIMESAT: A Software Package for Time-Series Processing and Assessment of Vegetation Dynamics2015In: Remote Sensing Time Series / [ed] Claudia Kuenzer, Stefan Dech, Wolfgang Wagner, Springer, 2015, p. 141-158Chapter in book (Other academic)
    Abstract [en]

    Large volumes of data from satellite sensors with high time-resolution 6 exist today, e.g. Advanced Very High Resolution Radiometer (AVHRR) and 7 Moderate Resolution Imaging Spectroradiometer (MODIS), calling for efficient 8 data processing methods. TIMESAT is a free software package for processing 9 satellite time-series data in order to investigate problems related to global change 10 and monitoring of vegetation resources. The assumptions behind TIMESAT are 11 that the sensor data represent the seasonal vegetation signal in a meaningful way, 12 and that the underlying vegetation variation is smooth. A number of processing 13 steps are taken to transform the noisy signals into smooth seasonal curves, including 14 fitting asymmetric Gaussian or logistic functions, or smoothing the data using a 15 modified Savitzky-Golay filter. TIMESAT can adapt to the upper envelope of the 16 data, accounting for negatively biased noise, and can take missing data and quality 17 flags into account. The software enables the extraction of seasonality parameters, 18 like the beginning and end of the growing season, its length, integrated values, etc. 19 TIMESAT has been used in a large number of applied studies for phenology 20 parameter extraction, data smoothing, and general data quality improvement. To 21 enable efficient analysis of future Earth Observation data sets, developments of 22 TIMESAT are directed towards processing of high-spatial resolution data from 23 e.g. Landsat and Sentinel-2, and use of spatio-temporal data processing methods.

  • 29. Eklundh, Lars
    et al.
    Jönsson, Per
    Malmö högskola, Faculty of Technology and Society (TS).
    TIMESAT for Processing Time-Series Data from Satellite Sensors for Land Surface Monitoring2016In: Multitemporal Remote Sensing / [ed] Yifang Ban, Springer, Cham , 2016, p. 177-194Chapter in book (Other academic)
    Abstract [en]

    Abstract. The TIMESAT software package has been developed to enable monitoring of dynamic land surface processes using remotely sensed data. The monitoring capability is based on processing of time-series for each image pixel using either of three smoothing methods included in TIMESAT: asymmetric Gaussian fits, double-logistic fits, and Savitzky-Golay filtering. The methods have different properties and are suitable for a wide range of data with different character and noise properties. The fitting methods can be upper-envelope weighted and can take quality data into account. Based on the fitted functions, growing season parameters are then extracted (beginning, end, amplitude, slope, integral, etc.), and can be merged into images. TIMESAT has been used in a number of application fields: mapping of phenology and phenological variations; ecological disturbances; vegetation classification and characterization; agriculture applications; climate applications; and for improving remote sensing signal quality. Future developments of TIMESAT will include new methods to better handle long gaps in time-series, handling of irregular time sampling, improved smoothing methods, and incorporation of the spatial domain. These modifications will enable use of TIMESAT also for high-resolution data, e.g. data from the planned ESA Sentinel-2 satellite.

  • 30.
    Ekman, Jörgen
    et al.
    Malmö högskola, School of Technology (TS).
    Grumer, Jon
    Hartman, Henrik
    Malmö högskola, School of Technology (TS).
    Jönsson, Per
    Malmö högskola, School of Technology (TS).
    A spectral study of Te V from MCDHF calculations2013In: Journal of Physics B: Atomic, Molecular and Optical Physics, ISSN 0953-4075, E-ISSN 1361-6455, Vol. 46, no 9, article id 095001Article in journal (Refereed)
    Abstract [en]

    State-of-the-art multiconfiguration Dirac-Hartree-Fock calculations for Te V have been performed and energies, LS-compositions, radiative lifetimes and Landé gJ-factors for 51 odd and even parity states are presented. In addition, predictions on transition rates and oscillator strengths for a multitude of transitions between these states are reported for the first time. To describe the atomic system accurately, by means of configuration interaction, valence and core-valence electron correlation effects were taken into account. Calculated energies and lifetimes of excited states agree very well with experimental data.

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  • 31.
    Ekman, Jörgen
    et al.
    Malmö University, Faculty of Technology and Society (TS), Department of Materials Science and Applied Mathematics (MTM).
    Jönsson, Per
    Malmö University, Faculty of Technology and Society (TS), Department of Materials Science and Applied Mathematics (MTM).
    Godefroid, M.
    Naze, C.
    Gaigalas, G.
    Bieron, J.
    RIS4: A program for relativistic isotope shift calculations2019In: Computer Physics Communications, ISSN 0010-4655, E-ISSN 1879-2944, Vol. 235, p. 433-446Article in journal (Refereed)
    Abstract [en]

    Spectral lines from different isotopes display a small separation in energy, commonly referred to as the line isotope shift. The program RIS4 (Relativistic Isotope Shift) calculates normal and specific mass shift parameters as well as field shift electronic factors from relativistic multiconfiguration Dirac-Hartree-Fock wave functions. These quantities, together with available nuclear data, determine isotope-dependent energy shifts. Using a reformulation of the field shift, it is possible to study, in a model-independent way, the atomic energy shifts arising from changes in nuclear charge distributions, e.g. deformations. (C) 2018 Published by Elsevier B.V.

  • 32.
    Ekman, Jörgen
    et al.
    Malmö högskola, School of Technology (TS).
    Jönsson, Per
    Malmö högskola, School of Technology (TS).
    Gustafsson, Stefan
    Malmö högskola, School of Technology (TS).
    Hartman, Henrik
    Malmö högskola, School of Technology (TS).
    du Rietz, Rickard
    Malmö högskola, School of Technology (TS).
    Gaigalas, Gediminas
    Godefroid, Michel
    Froese Fischer, Charlotte
    Massive Calculations of Atomic Properties with High Accuracy for Boron-like Iron and other Ions of Astrophysical Interest2013In: Book of abstracts;Abstract ID 17748, Institute of Modern Physics, Chinese Academy of Sciences , 2013Conference paper (Other academic)
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  • 33.
    Ekman, Jörgen
    et al.
    Malmö högskola, School of Technology (TS).
    Jönsson, Per
    Malmö högskola, School of Technology (TS).
    Gustafsson, Stefan
    Malmö högskola, School of Technology (TS).
    Hartman, Henrik
    Malmö högskola, School of Technology (TS).
    Gaigalas, Gediminas
    Godefroid, Michel R.
    Froese Fischer, Charlotte
    Calculations with spectroscopic accuracy: energies, transition rates, and Landé g_J-factors in the carbon isoelectronic sequence from Ar XIII to Zn XXV2014In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 564, article id A24Article in journal (Refereed)
    Abstract [en]

    Extensive self-consistent multiconfiguration Dirac-Hartree-Fock (MCDHF) calculations and subsequent relativistic configuration in- teraction calculations are performed for 262 states belonging to the 15 configurations 2s22p2, 2s2p3, 2p4, 2s22p3l, 2s2p23l, 2p33l and 2s22p4l (l = 0,1,2) in selected carbon-like ions from Ar XIII to Zn XXV. Electron correlation effects are accounted for through large configuration state function expansions. Calculated energy levels are compared with existing theoretical calculations and data from the Chianti and NIST databases. In addition, Landé gJ -factors and radiative electric dipole transition rates are given for all ions. The accuracy of the calculations are high enough to facilitate the identification of observed spectral lines.

  • 34.
    Ekman, Jörgen
    et al.
    Malmö University, Faculty of Technology and Society (TS), Department of Materials Science and Applied Mathematics (MTM).
    Jönsson, Per
    Malmö University, Faculty of Technology and Society (TS), Department of Materials Science and Applied Mathematics (MTM).
    Radziute, L.
    Gaigalas, G.
    Del Zanna, G.
    Grant, I. P.
    Large-scale calculations of atomic level and transition properties in the aluminum isoelectronic sequence from Ti X through Kr XXIV, Xe XLII, and W LXII2018In: Atomic Data and Nuclear Data Tables, ISSN 0092-640X, E-ISSN 1090-2090, Vol. 120, p. 152-262Article in journal (Refereed)
    Abstract [en]

    Large-scale self-consistent multiconfiguration Dirac-Hartree-Fock subsequent relativistic configuration interaction (RCl) calculations are reported for 360 states belonging to the 30 configurations 3s(2))3l, 4l. 5l}, 3p(2) (3d, 4l}, 3s(3p(2). 3d(2)),3s{3p3d, 3p4l. 3p5s, 3d4l'}, 3p3d(2), 3p(3) and 3d(3) with I = 0, 1,, n - 1 and l' = 0. 1. 2 in 17 systems of the aluminum-like isoelectronic sequence: Ti X through Kr XXIV, Xe XLII, and W LXII. Effects from electron correlation are taken into account by means of large expansions in terms of a basis of configuration state functions (CSF) and calculated energy levels are compared with existing theoretical calculations and the NIST Atomic Spectra database. Radiative E1, E2, M1 and M2 transition rates and associated lifetimes of energy levels are presented in online tables. The uncertainties of the calculated energies are very small, on average between 0.02% and 0.05%, which aid new line identifications in laboratory and astronomical spectra and also make it possible to find and rule out misidentifications. The uncertainties of the El transition probabilities, based on the agreement between values in the length and velocity gauges, are estimated to be of the order 0.5% for the strong transitions and 25% for the weaker intercombination transitions. The M1 transition values are not sensitive to electron correlation and are believed to be accurate to well within 1%. (C) 2017 Published by Elsevier Inc.

  • 35. Filippin, Livio
    et al.
    Beerwerth, Randolf
    Ekman, Jörgen
    Malmö högskola, Faculty of Technology and Society (TS).
    Fritzsche, Stephan
    Godefroid, Michel
    Jönsson, Per
    Malmö högskola, Faculty of Technology and Society (TS).
    Multiconfiguration calculations of electronic isotope shift factors in Al I2016In: Physical Review A. Atomic, Molecular, and Optical Physics, ISSN 1050-2947, E-ISSN 1094-1622, Vol. 94, no 6 : 062508, article id 62508Article in journal (Refereed)
    Abstract [en]

    The present work reports results from systematic multiconfiguration Dirac–Hartree–Fock calculations of electronic isotope shift factors for a set of transitions between low-lying levels of neutral aluminium. These electronic quantities together with observed isotope shifts between different pairs of isotopes provide the changes in mean-square charge radii of the atomic nuclei. Two computational approaches are adopted for the estimation of the mass- and field-shift factors. Within these approaches, different models for electron correlation are explored in a systematic way to determine a reliable computational strategy and to estimate theoretical error bars of the isotope shift factors.

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  • 36. Filippin, Livio
    et al.
    Bieron, Jacek
    Gaigalas, Gediminas
    Godefroid, Michel
    Jönsson, Per
    Malmö högskola, Faculty of Technology and Society (TS).
    Multiconfiguration calculations of electronic isotope-shift factors in Zn I2017In: Physical Review A: covering atomic, molecular, and optical physics and quantum information, ISSN 2469-9926, E-ISSN 2469-9934, Vol. 96, no 4, article id 10042502Article in journal (Refereed)
    Abstract [en]

    The present work reports results from systematic multiconfiguration Dirac-Hartree-Fock calculations of electronic isotope-shift factors for a set of transitions between low-lying states in neutral zinc. These electronic quantities, together with observed isotope shifts between different pairs of isotopes, provide the changes in mean-square charge radii of the atomic nuclei.Within this computational approach, different models for electron correlation are explored in a systematic way to determine a reliable computational strategy and to estimate theoretical error bars of the isotope-shift factors.

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  • 37. Filippin, Livio
    et al.
    Godefroid, Michel
    Ekman, Jörgen
    Malmö högskola, Faculty of Technology and Society (TS).
    Jönsson, Per
    Malmö högskola, Faculty of Technology and Society (TS).
    Core correlation effects in multiconfiguration calculations of isotope shifts in Mg I2016In: Physical Review A: covering atomic, molecular, and optical physics and quantum information, ISSN 2469-9926, E-ISSN 2469-9934, Vol. 93, no 6, article id 062512Article in journal (Refereed)
    Abstract [en]

    The present work reports results from systematic multiconfiguration Dirac-Hartree-Fock calculations of isotope shifts for several well-known transitions in neutral magnesium. Relativistic normal and specific mass shift factors as well as the electronic probability density at the origin are calculated. Combining these electronic quantities with available nuclear data, energy and transition level shifts are determined for the Mg26−Mg24 pair of isotopes. Different models for electron correlation are adopted. It is shown that, although valence and core-valence models provide accurate values for the isotope shifts, the inclusion of core-core excitations in the computational strategy significantly improves the accuracy of the transition energies and normal mass shift factors.

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  • 38. Fischer, Charlotte Froese
    et al.
    Gaigalas, G.
    Jönsson, Per
    Malmö University, Faculty of Technology and Society (TS), Department of Materials Science and Applied Mathematics (MTM).
    Bieron, J.
    GRASP2018-A Fortran 95 version of the General Relativistic Atomic Structure Package2019In: Computer Physics Communications, ISSN 0010-4655, E-ISSN 1879-2944, Vol. 237, p. 184-187Article in journal (Refereed)
    Abstract [en]

    The present GRASP2018 is an updated Fortran 95 version of the recommended block versions of programs from GRASP2K Version 1_1 for large-scale calculations Jonsson et al. (2013). MPI programs are included so that all major tasks can be executed using parallel computers. Tools have been added that simplify the generation of configuration state function expansions for the multireference single- and double computational model. Names of programs have been changed to accurately reflect the task performed by the code. Modifications to the relativistic self-consistent field program have been made that, in some instances, greatly reduce the number of iterations needed for determining the requested eigenvalues and the memory required. Changes have been made to the relativistic configuration interaction program to substantially cut down on the time for constructing the Hamiltonian matrix for configuration state function expansions based on large ,orbital sets. In the case of a finite nucleus the grid points have been changed so that the first non-zero point is Z-dependent as for the point nucleus. A number of tools have been developed to generate LaTeX tables of eigenvalue composition, energies, transition data and lifetimes. Tools for plotting and analyzing computed properties along an iso-electronic sequence have also been added. A number of minor errors have been corrected. A detailed manual is included that describes different aspects of the package as well as the steps needed in order to produce reliable results. Program summary Program Title: GRAsp2018 Program Files doi: http://dx.doi.org/10.17632/x574wpp2vg.1 Licensing provisions: MIT license Programming language: Fortran 95. Nature of problem: Prediction of atomic properties - atomic energy levels, isotope shifts, oscillator strengths, radiative decay rates, hyperfine structure parameters, specific mass shift parameters, Zeeman effects - using a multiconfiguration Dirac-Hartree-Fock approach. Solution method: The computational method is the same as in the previous GRASP2K [1,2] version except that only the latest recommended versions of certain routines are included. Restrictions: All calculations are for bound state solutions. Instead of relying on packing algorithms for specifying arguments of arrays of integrals, orbitals are designated by a "short integer" requiring one byte of memory for a maximum of 127 orbitals. The tables of reduced coefficients of fractional parentage used in this version are limited to sub-shells with j <= 9/2 [3]; occupied sub-shells with j > 9/2 are, therefore, restricted to a maximum of two electrons. Some other parameters, such as the maximum number of orbitals are determined in a parameter_def _M.f 90 file that can be modified prior to compile time. Unusual features: Parallel versions are available for several applications. References [1] P. Jonsson, X. He, C. Froese Fischer, and I. P. Grant, Comput. Phys. Commun. 176, 597 (2007). [2] P. Jonsson, G. Gaigalas, J. Bieron, C. Froese Fischer, and I. P. Grant, Comput. Phys. Commun. 184, 2197 (2013). [3] G. Gaigalas, S. Fritzsche, Z. Rudzikas, Atomic Data and Nuclear Data Tables 76, 235 (2000). (C) 2018 Elsevier B.V. All rights reserved.

  • 39. Fischer, Charlotte Froese
    et al.
    Gaigalas, Gediminas
    Jönsson, Per
    Malmö högskola, Faculty of Technology and Society (TS).
    Core Effects on Transition Energies for 3dk Configurations in Tungsten Ions2017In: Atoms, E-ISSN 2218-2004, Vol. 5, no 1, article id 7Article in journal (Refereed)
    Abstract [en]

    All energy levels of the 3k = 1,2,..., 8, 9, configurations for tungsten ions, computed using the GRASP2K fully relativistic code based on the variational multiconfiguration Dirac-Hartree-Fock method, are reported. Included in the calculations are valence correlation where all orbitals are considered to be valence orbitals, as well as core-valence and core-core effects from the subshells. Results are compared with other recent theory and with levels obtained from the wavelengths of lines observed in the experimental spectra. It is shown that the core correlation effects considerably reduce the disagreement with levels linked directly to observed wavelengths, but may differ significantly from the NIST levels, where an unknown shift of the levels could not be determined from experimental wavelengths. For low values of k, levels were in good agreement with relativistic many-body perturbation levels, but for, the present results were in better agreement with observation.

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  • 40. Froese Fischer, Charlotte
    et al.
    Godefroid, Michel
    Brage, Tomas
    Jönsson, Per
    Malmö högskola, Faculty of Technology and Society (TS).
    Gaigalas, Gediminas
    Advanced multiconfiguration methods for complex atoms: I. Energies and wave functions2016In: Journal of Physics B: Atomic, Molecular and Optical Physics, ISSN 0953-4075, E-ISSN 1361-6455, Vol. 49, no 18, article id 143Article in journal (Refereed)
    Abstract [en]

    Multiconfiguration wave function expansions combined with configuration interaction methods are a method of choice for complex atoms where atomic state functions are expanded in a basis of configuration state functions. Combined with a variational method such as the multiconfiguration Hartree–Fock (MCHF) or multiconfiguration Dirac–Hartree–Fock (MCDHF), the associated set of radial functions can be optimized for the levels of interest. The present review updates the variational MCHF theory to include MCDHF, describes the multireference single and double process for generating expansions and the systematic procedure of a computational scheme for monitoring convergence. It focuses on the calculations of energies and wave functions from which other atomic properties can be predicted such as transition rates, hyperfine structures and isotope shifts, for example.

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  • 41. Froese Fischer, Charlotte
    et al.
    Godefroid, Michel
    Verdebout, Simon
    Gaigalas, Gediminas
    Jönsson, Per
    Malmö högskola, School of Technology (TS).
    Configuration interaction with separately optimized pair correlation functions2010Conference paper (Other academic)
    Abstract [en]

    Variational methods produce one-electron radial functions that minimize the total energy of the system. Independent pair correlation functions (PCFs) designed to represent a specific correlation effect – valence, core-valence, or core-core – can be obtained from multiconfiguration Hartree-Fock (MCHF) or Dirac-Hartree-Fock (MCDHF) calculations [1,2]. These separately optimized and nonorthogonal PCFs may then be coupled by solving the associated generalized eigenproblem. In the present study, the Hamiltonian and overlap matrix elements are evaluated through biorthonormal orbital transformations and efficient counter-transformation of the configuration interaction eigenvectors [3]. The ground state of Be atom has been thoroughly tested by this method for various computational strategies and correlation models. It has been shown that the energy convergence is faster than with the usual SD-MCHF method of optimizing a single, orthonormal, one-electron orbital basis spanning the complete configuration space. Beryllium is a small system for which basis saturation can be achieved through complete active space MCHF expansions. But for larger systems describing electron correlation in all space by optimizing a common orthonormal set becomes hopeless whereas the calculation of additional PCFs is straight forward. Our independent optimization scheme, raises many questions related in the choice of the zero-order model to be used when building the interaction matrix. The present study is the first step in the current development of the extension of the atsp2K and grasp2K packages [1,2] that will adopt the biorthonormal treatment for energies, isotope shifts, hyperfine structures and transition probabilities.

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  • 42. Froese Fischer, Charlotte
    et al.
    Verdebout, Simon
    Godefroid, Michel
    Rynkun, Pavel
    Jönsson, Per
    Malmö högskola, School of Technology (TS).
    Gaigalas, Gediminas
    Doublet-quartet energy separation in boron: a partitioned-correlationfunction- interaction method2013In: Physical Review A. Atomic, Molecular, and Optical Physics, ISSN 1050-2947, E-ISSN 1094-1622, Vol. 88, no 6, article id 062506Article in journal (Refereed)
    Abstract [en]

    No lines have been observed for transitions between the doublet and quartet levels of B I. Consequently, energy levels based on observation for the latter are obtained through extrapolation of wavelengths along the isoelectronic sequence for the 2s22p 2Po 3/2 – 2s2p2 4P5/2 transition. In this paper, accurate theoretical excitation energies from a partitioned-correlation-function-interaction (PCFI) method are reported for B I that include both relativistic effects in the Breit-Pauli approximation and a finite mass correction. Results are compared with extrapolated values from observed data. For B I our estimate of the excitation energy 28 959 ± 5 cm−1 is in better agreement with the values obtained by Edl´en et al. (1969) than those reported by Kramida and Ryabtsev (2007). Our method is validated by applying the same procedure to the separation of these levels in C II.

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  • 43. Gaidamauskas, Erikas
    et al.
    Rynkun, Pavel
    Naze, Cedric
    Gaigalas, Gediminas
    Jönsson, Per
    Malmö högskola, School of Technology (TS).
    Godefroid, Michel
    Tensorial form and matrix elements of the relativistic nuclear recoil operator2011In: Journal of Physics B: Atomic, Molecular and Optical Physics, ISSN 0953-4075, E-ISSN 1361-6455, Vol. 44, no 17, article id 175003Article in journal (Refereed)
    Abstract [en]

    Within the lowest-order relativistic approximation (∼v2/c2) and to first order in me/M, the tensorial form of the relativistic corrections of the nuclear recoil Hamiltonian is derived, opening interesting perspectives for calculating isotope shifts in the multiconfiguration Dirac–Hartree–Fock framework. Their calculation is illustrated for selected Li-, B- and C-like ions. This work underlines the fact that the relativistic corrections to the nuclear recoil are definitively necessary for obtaining reliable isotope shift values.

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  • 44.
    Gaigalas, G.
    et al.
    Vilnius University, Lithuania.
    Rynkun, P.
    Vilnius University, Lithuania.
    Radziute, L.
    Vilnius University, Lithuania.
    Jönsson, Per
    Malmö University, Faculty of Technology and Society (TS), Department of Materials Science and Applied Mathematics (MTM).
    Wang, K.
    Hebei University, China; Fudan University, China.
    Energy and transition data computations for P-like ions: As, Kr, Sr, Zr, Mo, and W2021In: Atomic Data and Nuclear Data Tables, ISSN 0092-640X, E-ISSN 1090-2090, Vol. 141, article id 101428Article in journal (Refereed)
    Abstract [en]

    The multiconfiguration Dirac-Hartree-Fock (MCDHF) and relativistic configuration interaction (RCI) methods were used to compute excitation energies and transition data for the 147 lowest states of the even 3s(3)p(4), 3s(2)3p2(3)d, 3p(4)3d, 3s(3)p(2)3d(2) configurations and for the 124 lowest states of the odd 3s23p3, 3p5, 3s3p33d, 3s(2)3p(3)d2, 3p(3)3d(2) configurations for the P-like ions: As XIX, Kr XXII, Sr XXIV, Zr XXVI, Mo XXVIII, and W LX. E1 transition rates and weighted oscillator strengths among these states are given. Valence-valence, core-valence and core-core electron correlation effects are included. Computed excitation energies and transition data are compared with the NIST recommended values and experimental or theoretical results of other authors. All calculations were performed using the general relativistic atomic structure package GRASP2018. (C) 2021 Elsevier Inc. All rights reserved.

  • 45. Gaigalas, Gediminas
    et al.
    Fischer, Charlotte Froese
    Rynkun, Pavel
    Jönsson, Per
    Malmö högskola, Faculty of Technology and Society (TS).
    JJ2LSJ Transformation and Unique Labeling for Energy Levels2017In: Atoms, E-ISSN 2218-2004, Vol. 5, no 1Article in journal (Refereed)
    Abstract [en]

    The JJ2LSJ program, which is important not only for the GRASP2K package but for the atom theory in general, is presented. The program performs the transformation of atomic state functions (ASFs) from coupled CSF basis. In addition, the program implements a procedure that assigns a unique label to all energy levels. Examples of how to use the JJ2LSJ program are given. Several cases are presented where there is a unique labeling problem.

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  • 46. Gaigalas, Gediminas
    et al.
    Gaidamauskas, Erikas
    Bieron, Jacek
    Fritzsche, Stefan
    Jönsson, Per
    Malmö högskola, School of Teacher Education (LUT), Nature-Environment-Society (NMS).
    MCDHF calculations of the electric dipole moment of radium induced by the nuclear Schiff moment2008Conference paper (Other (popular science, discussion, etc.))
  • 47. Gaigalas, Gediminas
    et al.
    Gaidamauskas, Erikas
    Jönsson, Per
    Malmö högskola, School of Teacher Education (LUT), Nature-Environment-Society (NMS).
    Multiconfiguration Dirac-Hartree-Fock calculations for the hyperfine-structure parameters and the scalar-pseudoscalar interaction constant of 133Cs2008In: Journal of Physics: Conference Series, Vol. 139, no 130, article id 012008Article in journal (Refereed)
    Abstract [en]

    In this work we investigate the applicability of the multiconfiguration Dirac-Hartree-Fock (MCDHF) method for calculating parity and time reversal symmetry violations in many-electron atoms. As an example we show results from calculations of the scalarpseudoscalar interaction constant for 133Cs. Calculated limits of this interaction constant are in a good agreement with other theories.

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  • 48. Gaigalas, Gediminas
    et al.
    Jönsson, Per
    Malmö högskola, School of Technology (TS).
    Alkauskas, Andrius
    Energies for States of the 2s22p5 and 2s2p6 in Fluorine-like Ions Between Si VI and W LXVI2012In: Program and Abstracts: Eighth International Conference on Atomic and Molecular Data and Their Applications: ICAMDATA 8, 2012, p. 74-74Conference paper (Other academic)
    Abstract [en]

    The experimental energy levels and computed energies from the largest RCI calculations including QED corrections are displayed in Table 1. The computed energies agree very well with experimental values. Starting from Si VI the energy differences rapidly goes down to a few hundred cm−1 , which corresponds to an error of around 0.02 %. From Sr XXX to Sn XLII experimental energies are given with error bars between 1000 and 2000 cm−1 . The calculated values are within the stated experimental error bars except for Cd XL and Sn XLII. The reason for the difference in these two ions is not known. Experimental data for ions from Sb XLIII to Ta LXV are not available. For the W LXVI ion, the differences between theoretical and experimental transition energies are a few thousand cm−1 . As discussed by Kramida [1] the total uncertainties of the measured energies in W LXVI were dominated by the calibration uncertainties and varied in the range 1.0 - 2.3 eV, which translates to 8000 - 20000 cm−1 . Based on the comparison between theory and experiment for the lighter ions as well as for W LXVI we estimate that the errors in the calculated transition energies for ions in the range Sb XLIII - Ta LXV, for which no experimental data are available, are less than 0.08 %.

  • 49. Gaigalas, Gediminas
    et al.
    Kato, Daiji
    Jönsson, Per
    Malmö högskola, School of Technology (TS).
    Rynkun, Pavel
    Radziute, Laima
    Energy level structure of Er3+ free ion and Er3+ ion in Er2O3 crystal2014In: National Institute for Fusion Science, Research Report NIFS-DATA, ISSN 0915-6364, no 115, p. 1-25Article in journal (Other academic)
    Abstract [en]

    The latest version of the GRASP2K atomic structure package [P. J¨onsson, G. Gaigalas, J. Biero´n, C. Froese Fischer, I.P. Grant, Comput. Phys. Commun. 184 (2013) 2197], based on the multiconfigurational Dirac-Hartree-Fock method, is extended to account for effects of crystal fields in complex systems. Energies from relativistic configuration interaction calculations are reported for the Er3+ free ion. E2 and M1 line strengths, weighted oscillator strengths, and rates are presented for transitions between states of the [Xe]4f11 configuration. Also Stark levels of the Er3+ 4Io 15/2 state in Er2O3 are calculated in the ab initio point charge crystal field approximation. In all calculations the Breit interaction and leading QED effects are included as perturbations. Different strategies for describing electron correlation effects are tested and evaluated. The final results are compared with experiment and other methods.

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  • 50. Gaigalas, Gediminas
    et al.
    Rynkun, Pavel
    Radziute, Laima
    Kato, Daiji
    Tanaka, Masaomi
    Jönsson, Per
    Malmö University, Faculty of Technology and Society (TS), Department of Materials Science and Applied Mathematics (MTM).
    Energy Level Structure and Transition Data of Er2+2020In: Astrophysical Journal Supplement Series, ISSN 0067-0049, E-ISSN 1538-4365, Vol. 248, no 1, article id 13Article in journal (Refereed)
    Abstract [en]

    A majority of Er in the universe is synthesized by the r-process, which can occur in the mergers of neutron stars (NSs). The contribution of this element to the opacity of NS ejecta should be tested, but even the energy levels of first excited configuration have not been fully presented. The main aim of this paper is to present accurate energy levels of the ground [Xe]4f(12) and first excited [Xe]4f(11)5d configurations of Er2+. The energy level structure of the Er2+ ion was computed using the multiconfiguration Dirac-Hartree-Fock and relativistic configuration interaction (RCI) methods, as implemented in the GRASP2018 program package. The Breit interaction, self-energy, and vacuum polarization corrections were included in the RCI computations. The zero-first-order approach was used in the computations. Energy levels with the identification in LS coupling for all (399) states belonging to the [Xe]4f(12) and [Xe]4f(11)5d configurations are presented. Electric dipole (E1) transition data between the levels of these two configurations are computed. The accuracy of these data is evaluated by studying the behavior of the transition rates as functions of the gauge parameter, as well as by evaluating the cancellation factors. The core electron correlations were studied using different strategies. The rms deviations obtained in this study for states of the ground and excited configurations from the available experimental data are 649 and 754 cm(-1), respectively.

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