| 1. |
- Gaigalas, Gediminas, et al.
(författare)
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Energy Level Structure and Transition Data of Er2
- 2020
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Ingår i: Astrophysical Journal Supplement Series. - : Institute of Physics Publishing (IOPP). - 0067-0049 .- 1538-4365. ; 248:1
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Tidskriftsartikel (refereegranskat)abstract
- 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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| 2. |
- Gaigalas, Gediminas, et al.
(författare)
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Energy level structure of Er3+ free ion and Er3+ ion in Er2O3 crystal
- 2014
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Ingår i: National Institute for Fusion Science, Research Report NIFS-DATA. - : National Institute for Fusion Science. - 0915-6364. ; :115, s. 1-25
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- 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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| 3. |
- 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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| 4. |
- Mozuraitis, Raimondas, et al.
(författare)
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Hippophae rhamnoides berry related Pichia kudriavzevii yeast volatiles modify behaviour of Rhagoletis batava flies
- 2020
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Ingår i: Journal of Advanced Research. - : Elsevier BV. - 2090-1232 .- 2090-1224. ; 21, s. 71-77
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Tidskriftsartikel (refereegranskat)abstract
- Olfactory cues have a large impact on insect behaviour and fitness consequently showing potential in pest management. Yeast released volatiles are used by insects as olfactory cues for finding feeding and oviposition sites. The yeast strain SB-16-15 was isolated from spontaneous fermentation of Hippophae rhamnoides berries and identified as Pichia kudriavzevii. Thirty-nine volatiles were sampled from the headspace of P. kudriavzevii yeasts by solid phase micro extraction and identified by gas chromatography and mass spectrometry techniques. Ten of those volatiles elicited antennal responses of Rhagoletis batava flies, one of the most serious pest of H. rhamnoides berries. In the two-choice experiments, R. batava flies preferred the mixture composed of nine synthetic compounds analogous to electroanntenographic active volatiles released by the yeasts compare to the solvent control. Female flies were significantly attracted to the mixture at the concentration 0.1 mu L mL(-1) and showed no preference to the mixture at the Peer concentration 1 mu L mL(-1) versus control while males reacted positively to the synthetic blend at the concentration 1 mu L mL(-1). Herein, for the first time, behaviour modifying effect of H. rhamnoides berry related yeast volatiles was shown suggesting these semiochemicals have potential in use for monitoring R. batava flies.
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| 5. |
- Papoulia, Asimina, et al.
(författare)
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Coulomb (Velocity) Gauge Recommended in Multiconfiguration Calculations of Transition Data Involving Rydberg Series
- 2019
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Ingår i: Atoms. - : MDPI. - 2218-2004. ; 7:4
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Tidskriftsartikel (refereegranskat)abstract
- Astronomical spectroscopy has recently expanded into the near-infrared (nIR) wavelength region, raising the demands on atomic transition data. The interpretation of the observed spectra largely relies on theoretical results, and progress towards the production of accurate theoretical data must continuously be made. Spectrum calculations that target multiple atomic states at the same time are by no means trivial. Further, numerous atomic systems involve Rydberg series, which are associated with additional difficulties. In this work, we demonstrate how the challenges in the computations of Rydberg series can be handled in large-scale multiconfiguration Dirac-Hartree-Fock (MCDHF) and relativistic configuration interaction (RCI) calculations. By paying special attention to the construction of the radial orbital basis that builds the atomic state functions, transition data that are weakly sensitive to the choice of gauge can be obtained. Additionally, we show that the Babushkin gauge should not always be considered as the preferred gauge, and that, in the computations of transition data involving Rydberg series, the Coulomb gauge could be more appropriate for the analysis of astrophysical spectra. To illustrate the above, results from computations of transitions involving Rydberg series in the astrophysically important C IV and C III ions are presented and analyzed.
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| 6. |
- Radziute, Laima, et al.
(författare)
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Electric dipole moments of superheavy elements : A case study on copernicium
- 2016
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Ingår i: Physical Review A: covering atomic, molecular, and optical physics and quantum information. - : American Physical Society. - 2469-9926 .- 2469-9934. ; 93:6
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Tidskriftsartikel (refereegranskat)abstract
- The multiconfiguration Dirac-Hartree-Fock method was employed to calculate the atomic electric dipole moments (EDMs) of the superheavy element copernicium (Cn, Z = 112). The EDM enhancement factors of Cn, calculated here, are about one order of magnitude larger than those of Hg. The exponential dependence of the enhancement factors on the atomic number Z along group 12 of the periodic table was derived from the EDMs of the entire homologous series, Zn, Cd, Hg, Cn, and Uhb. These results show that superheavy elements with sufficiently long half-lives are potential candidates for EDM searches.
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| 7. |
- Radziute, Laima, et al.
(författare)
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Energy level structure of Er3
- 2014
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Ingår i: Journal of Quantitative Spectroscopy and Radiative Transfer. - : Elsevier. - 0022-4073 .- 1879-1352. ; 152, s. 94-106
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Tidskriftsartikel (refereegranskat)abstract
- AtomicenergylevelsandE2andM1transitionratesarereportedforthe[Xe]4f11 ground configurationinEr3þ from relativisticmulticonfigurationDirac–Hartree–Fockandcon- figuration interactioncalculations.TheBreittransverseinteractionandleadingQED effectsareincludedasperturbations.Differentstrategiesfordescribingelectroncorrela- tion effectsaretestedandevaluated.Thecalculatedenergylevelsarecomparedwith experimentandresultsfromsemi-empiricalmethods.
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| 8. |
- Radziute, Laima, et al.
(författare)
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Energy level structure of Er3+ free ion
- 2014
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Ingår i: Ninth International Conference on Atomic and Molecular Data and Their Applications: book of abstracts. ; , s. 91-91
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Ab initio calculations for the Er3+ ion are performed using GRASP2K package, based on multiconfigurational Dirac-Hartree-Fock method (MCDHF). 41 energy levels of the [Xe]4f 11 con- figuration are calculated. The study includes different types of correlations using different strategies. The Breit interaction and leading QED effects are included as perturbations in all calculations. We present the results of the 10 lowest levels (see Table 1), obtained by single and double excitations corresponding to valence, core, and core-valence correlations. Levels are notated in the form (2S+1)L Nr J , where instead of the group labels νW U, single character ”numbers” Nr are used. Deviation of our values for energy levels from NIST database reaches 6.9%. Energy levels given at NIST are derived from the spectrum of Er3+ in LaF3 [1].
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| 9. |
- Radziute, Laima, et al.
(författare)
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Energy level structure of the ground configuration in the Er3+ free ion
- 2015
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Ingår i: Physica Scripta. - : Bibliopolis, Edizioni di Filosofia e Scienze. - 0031-8949 .- 1402-4896. ; 90:5
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Tidskriftsartikel (refereegranskat)abstract
- Energy levels of the ground configuration [Xe]4f11 in the Er3+ ion are reported from relativistic configuration interaction calculations. Calculations are performed using the relativistic atomic structure package GRASP2K, which implements the multiconfiguration Dirac–Hartree–Fock method. The Breit transverse interaction and leading QED effects are included as perturbations. The final energies of 41 levels are compared with results from experiment and semi-empirical methods.
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| 10. |
- Radziute, Laima, et al.
(författare)
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Extended calculations of level and transition properties in the nitrogen isoelectronic sequence : Cr XVIII, Fe XX, Ni XXII, and Zn XXIV
- 2015
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Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 582
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Tidskriftsartikel (refereegranskat)abstract
- Extensive multiconfiguration Dirac-Hartree-Fock (MCDHF) calculations and relativistic configuration interaction (RCI) calculations are performed for 272 states of the 2s22p3, 2s2p4, 2p5, 2s22p23l, 2s2p33l, and 2p43l (l = 0, 1, 2) configurations in the nitrogen-like ions Cr XVIII, Fe XX, Ni XXII, and Zn XXIV. Valence, core-valence, and core-core 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 NIST database. Landé gJ -factors; hyperfine structures; isotope shifts; and radiative electric dipole (E1), electric quadrupole (E2), and magnetic dipole (M1) transition rates are given for all ions. The accuracy of the calculated energy levels is high enough to facilitate identification of observed spectral lines involving the 2l43l configurations, for which experimental data
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| 11. |
- Radziute, Laima, et al.
(författare)
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Multiconfiguration Dirac-Hartree-Fock calculations of atomic electric dipole moments of 225Ra, 199Hg, and 171Yb
- 2014
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Ingår i: Physical Review A. Atomic, Molecular, and Optical Physics. - : American Physical Society. - 1050-2947 .- 1094-1622. ; 90
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Tidskriftsartikel (refereegranskat)abstract
- The multiconfiguration Dirac-Hartree-Fock method is employed to calculate atomic electric dipole moments in the ground states of 225Ra, 199Hg, and 171Yb. For the calculations of the matrix elements we extend the relativistic atomic structure package GRASP2K. The extension includes programs to evaluate matrix elements of PT -odd electron-nucleus tensor-pseudotensor and pseudoscalar-scalar interactions, the atomic electric dipole operator, the nuclear Schiff moment, and the interaction of the electron electric dipole moment with nuclear magnetic moments. The interelectronic interactions are accounted for through valence and core-valence electron correlation effects. The electron shell relaxation is included with separately optimized wave functions of opposite parities.
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| 12. |
- Radziute, Laima, et al.
(författare)
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Weak- and hyperfine-interaction-induced 1s2s 1S0-1s2 1S0 E1 transition rates of He-like ions
- 2015
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Ingår i: Chinese Physics B. - : Institute of Physics Publishing (IOPP). - 1674-1056. ; 24:4
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Tidskriftsartikel (refereegranskat)abstract
- Weak- and hyperfine-interaction-induced 1s2s 1S0 -1s2 1S0 E1 transition rates for the isoelectronic sequence of He-like ions have been calculated using the multiconfiguration Dirac–Hartree–Fock (MCDHF) and relativistic configuration interaction methods. The results should be helpful for the future experimental investigations of parity non-conservation effects.
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