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Träfflista för sökning "WFRF:(Gaigalas Gediminas) "

Sökning: WFRF:(Gaigalas Gediminas)

  • Resultat 61-70 av 95
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61.
  • Naze, Cedric, et al. (författare)
  • Isotope shift parameters, hyperfine interaction constants and Landte factors along the Be, B, C and N isoelectronic sequences
  • 2012
  • Ingår i: Europhysics Conference Abstracts;36C. - : European Physical Society. ; , s. 143-143
  • Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
    • The mass shift parameters, the electron density at the origin, the hyperfine interaction constants and the gJ Land´e factors are computed along the beryllium, boron, carbon and nitrogen isoelectronic sequences. The calculations on B- and C-like ions are based on the wave functions described in [1-4]. The many-electron wave functions corresponding to the Be and N isoelectronic sequences are obtained using the new version of the grasp2K multiconfiguration Dirac-Fock package, following similar optimization strategies. A new program, hereafter referred as ris and designed as a module of grasp2K, calculates the mass shift parameters and the electron density at the origin within the relativistic framework. For estimating the mass shift, ris considers the expectation value of the following operator HMS = 1 2M N Xi , j pi · pj − αZ ri i + ( i · ri) ri r2 i · pj , that is more complete than the one calculated in sms92. The one-body part (i = j) of the first term of equation is responsible for the observed breakdown of the Dirac kinetic energy operator often used to evaluate the isotope normal mass shift. The second term of equation takes the nuclear recoil corrections into account at the (αZ) order. The programs ris and rhfs2 allow the storage of the angular coefficients to reduce the cpu time when calculations are performed along a given isoelectronic sequence.
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62.
  • Naze, Cedric, et al. (författare)
  • Isotope Shifts in Beryllium-, Boron-, Carbon-, and Nitrogen-like Ions from Relativistic Configuration Interaction Calculations
  • 2014
  • Ingår i: Atomic Data and Nuclear Data Tables. - : Elsevier. - 0092-640X .- 1090-2090. ; 100:5, s. 1197-1249
  • Tidskriftsartikel (refereegranskat)abstract
    • Energy levels, normal and specific mass shift parameters as well as electronic densities at the nucleus are reported for numerous states along the beryllium, boron, carbon, and nitrogen isoelectronic sequences. Combined with nuclear data, these electronic parameters can be used to determine values of level and transition isotope shifts. The calculation of the electronic parameters is done using first-order perturbation theory with relativistic configuration interaction wavefunctions that account for valence, core–valence, and core–core correlation effects as zero-order functions. Results are compared with experimental and other theoretical values, when available.
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63.
  • Naze, Cedric, et al. (författare)
  • RIS3 : a program for relativistic isotope shift calculations
  • 2013
  • Ingår i: Computer Physics Communications. - : Elsevier. - 0010-4655 .- 1879-2944. ; 184:9, s. 2187-2196
  • Tidskriftsartikel (refereegranskat)abstract
    • An atomic spectral line is characteristic of the element producing the spectrum. The line also depends on the isotope. The program ris3 (Relativistic Isotope Shift) calculates the electron density at the origin and the normal and speci c mass shift parameters. Combining these electronic quantities with available nuclear data, isotope-dependent energy level shifts are determined
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64.
  • Papoulia, Asimina, et al. (författare)
  • Ab initio electronic factors of the A and B hyperfine structure constants for the 5s(2)5p6s( 1,3)P(1)(0) states in Sn I
  • 2021
  • Ingår i: Physical Review A: covering atomic, molecular, and optical physics and quantum information. - : American Physical Society. - 2469-9926 .- 2469-9934. ; 103:2
  • Tidskriftsartikel (refereegranskat)abstract
    • Large-scale ab initio calculations of the electronic contribution to the electric quadrupole hyperfine constant B were performed for the 5s(2)5p6s( 1,3)P(1)(0)excited states of neutral tin. To probe the sensitivity of B to different electron correlation effects, three sets of variational multiconfiguration Dirac-Hartree-Fock and relativistic configuration interaction calculations employing different strategies were carried out. In addition, a fourth set of calculations was based on the configuration interaction Dirac-Fock-Sturm theory. For the 5s(2)5p6s( 1)P(1)(0) state, the final value of B/Q = 703(50) MHz/b differs by 0.4% from the one recently used by Yordanov et al. [Commun. Phys. 3, 107 (2020)] to extract the nuclear quadrupole moments Q for tin isotopes in the range Sn117-131 from collinear laser spectroscopy measurements. Efforts were made to provide a realistic theoretical uncertainty for the final B/Q value of the 5s(2)5p6s( 1)P(1)(0) state based on statistical principles and on correlation with the electronic contribution to the magnetic dipole hyperfine constant A.
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65.
  • Papoulia, Asimina, et al. (författare)
  • Ab initio electronic factors of the A and B hyperfine structure constants for the 5s25p6s1,3P01 states in Sn I
  • 2021
  • Ingår i: Physical Review A. - 2469-9926. ; 103:2
  • Tidskriftsartikel (refereegranskat)abstract
    • Large-scale ab initio calculations of the electronic contribution to the electric quadrupole hyperfine constant B were performed for the 5s25p6s1,3Po1 excited states of neutral tin. To probe the sensitivity of B to different electron correlation effects, three sets of variational multiconfiguration Dirac-Hartree-Fock and relativistic configuration interaction calculations employing different strategies were carried out. In addition, a fourth set of calculations was based on the configuration interaction Dirac-Fock-Sturm theory. For the 5s25p6s 1Po1 state, the final value of B/Q=703(50) MHz/b differs by 0.4% from the one recently used by Yordanov et al. [Commun. Phys. 3, 107 (2020)] to extract the nuclear quadrupole moments Q for tin isotopes in the range 117−131Sn from collinear laser spectroscopy measurements. Efforts were made to provide a realistic theoretical uncertainty for the final B/Q value of the 5s25p6s 1Po1 state based on statistical principles and on correlation with the electronic contribution to the magnetic dipole hyperfine constant A.
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66.
  • Papoulia, Asimina, et al. (författare)
  • Coulomb (Velocity) Gauge Recommended in Multiconfiguration Calculations of Transition Data Involving Rydberg Series
  • 2019
  • Ingår i: Atoms. - : MDPI. - 2218-2004. ; 7:4
  • 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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67.
  • Petryla, Andrius, et al. (författare)
  • Theoretical and experimental studies of In I, Sn II, Sb III, and Te IV atomic properties
  • 2012
  • Ingår i: Europhysics Conference Abstracts;36C. - : European Physical Society. ; , s. 42-42
  • Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
    • We use relativistic multiconfiguration Dirac-Hartree-Fock and configuration interaction calculations to study 5s2nl and 5s5p2 configurations of In I, Sn II, Sb III, and Te IV. Energies, transition amplitudes, Land´e gJ-factors, and hyperfine constants are calculated using a correlation model that accounts for valence and core-valence correlation. Also spin- and orbital polarization effects are accounted for by single excitations from all core-shells to an increasing set of active orbitals. Transformed to the LSJ-coupling scheme, using the new features of the GRASP2K program, the calculated wave functions shed light on the difficulties in labeling some states due to the extensive 5s25d and 5s5p2 configuration interaction. Our results are compared with experimental values and values from relativistic many-body perturbation theory (RMBPT) and all-order single-double (SD) calculations. The theoretical work is complemented with experiment, and new hyperfine interaction constants are derived for several states in In I from high resolution Fourier Transform Spectra.
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68.
  • Radziute, Laima, et al. (författare)
  • Electric dipole moments of superheavy elements : A case study on copernicium
  • 2016
  • Ingår i: Physical Review A: covering atomic, molecular, and optical physics and quantum information. - : American Physical Society. - 2469-9926 .- 2469-9934. ; 93:6
  • 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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69.
  • Radziute, Laima, et al. (författare)
  • Energy level structure of Er3
  • 2014
  • Ingår i: Journal of Quantitative Spectroscopy and Radiative Transfer. - : Elsevier. - 0022-4073 .- 1879-1352. ; 152, s. 94-106
  • 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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70.
  • Radziute, Laima, et al. (författare)
  • Energy level structure of Er3+ free ion
  • 2014
  • Ingår i: Ninth International Conference on Atomic and Molecular Data and Their Applications: book of abstracts. ; , s. 91-91
  • 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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  • Resultat 61-70 av 95

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