| 1. |
- Gaidamauskas, Erikas, et al.
(författare)
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Tensorial form and matrix elements of the relativistic nuclear recoil operator
- 2011
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Ingår i: Journal of Physics B. - : IOP Publishing Ltd. - 0953-4075 .- 1361-6455. ; 44:17
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Tidskriftsartikel (refereegranskat)abstract
- 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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| 2. |
- Li, Jiguang, et al.
(författare)
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Mass and field isotope shift parameters for the 2s-2p resonance doublet of Lithium-like ions
- 2012
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Ingår i: Book of Abstracts. ; , s. 219-219
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Recently, it was shown that the dielectronic recombination measurements can be used for accurately inferring changes in the nuclear mean-square charge radii of highly-charged lithium-like neodymium [1]. To make use of this method for other elements and isotopes, mass and field isotope shift calculations are required in order to derive information about the nuclear charge distributions. In this work [2], we estimate the relativistic mass and field isotope shift factors for the two 2s2 S1/2−2p 2Po 1/2,3/2 transitions along the lithium isoelectronic sequence using the GRASP2K package [3, 4] based on the multiconfiguration Dirac-Hartree-Fock method. The detailed comparisons with the MCDF-gme [5] calculations and others will be illustrated. Adopting the calculated electronic parameters of isotope shifts, we analyze the competition between the mass and field shift contributions for the 2s − 2p resonance doublet along the isoelectronic sequence, with the assistance of the empirical relations between Z and the nuclear properties. It is found that the mass shifts and the field shifts possess similar orders of magnitude in the Z < 40 range, so that one should consider both of them for a relevant analysis of isotope shifts. The field shift contribution grows rapidly towards the high-Z region and becomes quickly dominant. Discussions are also made for the 2s 2S1/2 − 2p 2Po 1/2,3/2 line isotope shifts in the case of 150,142 Nd 57+ where the experimental values are available. The present results show that the higher-order nuclear moments often neglected in the calculation of the field shift should be considered for very highly charged ions in order to extract the δ⟨r2⟩ values from experiments.
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| 3. |
- Li, Jiguang, et al.
(författare)
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Mass and field isotope shift parameters for the 2s - 2p resonance doublet of lithium-like ions (Göteborg)
- 2012
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Ingår i: Europhysics Conference Abstracts;36C. - : European Physical Society. ; , s. 76-76, s. 92-92
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Dielectronic recombination measurements have been proven to be a sensitive tool for deducing changes in the nuclear mean-square charge radii of highly-charged lithium-like neodymium. To make use of this method for other elements and isotopes, mass and field isotope shift calculations are required in order to derive information about the nuclear charge distributions. In this work, we estimate and discuss the relativistic mass and field isotope shift factors for the two 2s 2S1/2−2p 2Po 1/2,3/2 transitions along the lithium isoelectronic sequence. Using the GRASP2K package based on the multi-configuration Dirac-Fock method, the electron correlation and the Breit interaction are taken systematically into account in all the calculations. Adopting the calculated electronic parameters of isotope shifts, we qualitatively analyze the competition between the mass and field shift contributions for the 2s − 2p resonance doublet along the isoelectronic sequence, with the assistance of some empirical relations between Z and the nuclear properties. It is found that the mass shifts and the field shifts possess similar orders of magnitude in the Z < 40 range, so that one should consider both of them for a relevant analysis of isotope shifts, especially for extracting the nuclear mean-square charge radii. The field shift contribution grows rapidly towards the high-Z region and becomes quickly dominant. Quantitative discussions are also made for the 2s 2S1/2 − 2p 2Po 1/2,3/2 line isotope shifts in the case of 150,142Nd57+ for which experimental values are available. The present results show that the higher-order nuclear moments often neglected in the calculation of the field shift should be considered for very highly charged ions in order to extract the δhr2i values from experiments. The consistency between GRASP2K and MCDF-gme results will be illustrated.
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| 4. |
- Li, Jiguang, et al.
(författare)
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Mass- and field-shift isotope parameters for the 2s-2p resonance doublet of lithium-like ions
- 2012
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Ingår i: Physical Review A. Atomic, Molecular, and Optical Physics. - : Americal Physical Society. - 1050-2947 .- 1094-1622. ; 86:2
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Tidskriftsartikel (refereegranskat)abstract
- It was recently shown that dielectronic recombination measurements can be used for accurately inferring changes in the nuclear mean-square charge radii of highly charged lithiumlike neodymium [ Brandau et al. Phys. Rev. Lett. 100 073201 (2008)]. To make use of this method to derive information about the nuclear charge distribution for other elements and isotopes, accurate electronic isotope shift parameters are required. In this work, we calculate and discuss the relativistic mass- and field-shift factors for the two 2s 2S1/2-2p 2P1/2,3/2o transitions along the lithium isoelectronic sequence. Based on the multiconfiguration Dirac-Hartree-Fock method, the electron correlation and the Breit interaction are taken into account systematically. The analysis of the isotope shifts for these two transitions along the isoelectronic sequence demonstrates the importance and competition between the mass shifts and the field shifts.
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| 5. |
- Li, Jiguang, et al.
(författare)
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On the breakdown of the Dirac kinetic energy operator for estimating normal mass shifts
- 2012
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Ingår i: European Physical Journal D. - : EDP Sciences. - 1434-6060 .- 1434-6079. ; 66, s. 290-297
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Tidskriftsartikel (refereegranskat)abstract
- The Dirac kinetic energy (DKE) form of the normal mass shift operator (me/M ∑i=1N Ti), which is an approximation of the (1/2M ∑i=1N pi2) operator built on the relativistic electron momenta, is widely used in relativistic atomic structure calculations. In the present paper, we illustrate the progressive breakdown of the Dirac kinetic energy form relatively to the momentum form when increasing the nuclear charge along the lithium isoelectronic sequence. Both forms are incorrect in the relativistic case but the DKE operator provides expectation values that are closer to the results obtained with the more complete relativistic recoil operator.
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| 6. |
- Naze, Cedric, et al.
(författare)
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Isotope shift parameters, hyperfine interaction constants and Landte factors along the Be, B, C and N isoelectronic sequences
- 2012
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Ingår i: Europhysics Conference Abstracts;36C. - : European Physical Society. ; , s. 143-143
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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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| 7. |
- Naze, Cedric, et al.
(författare)
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Isotope Shifts in Beryllium-, Boron-, Carbon-, and Nitrogen-like Ions from Relativistic Configuration Interaction Calculations
- 2014
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Ingår i: Atomic Data and Nuclear Data Tables. - : Elsevier. - 0092-640X .- 1090-2090. ; 100:5, s. 1197-1249
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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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| 8. |
- Naze, Cedric, et al.
(författare)
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RIS3 : a program for relativistic isotope shift calculations
- 2013
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Ingår i: Computer Physics Communications. - : Elsevier. - 0010-4655 .- 1879-2944. ; 184:9, s. 2187-2196
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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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| 9. |
- Verdebout, Simon, et al.
(författare)
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Atomic properties of neutral Ne using the LCFI method
- 2011
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Ingår i: Abstracts 43rd Conference of the European Group for Atomic Systems (EGAS). - : European Physical Society. ; , s. 156-156
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- The localised correlation function interaction (LCFI) method, based on the biorthonormal orbital transformations and e cient counter-transformations of the con guration interaction eigenvectors [1], was shown to be e cient for describing the total energy of the beryllium atom [2]. Each localized correlation function (LCF) is dedicated to the description of the electronic correlation associated to a given electron pair. Such functions are produced, using the multicon guration Hartree-Fock (MCHF) and Dirac-Hartree-Fock (MCDHF) variational methods, by optimizing the correlation functions and the mixing coe cients on a tailored con guration space. Applying the LCFI method to neon allows us to quantify the contribution of each localized correlation function to di erent atomic properties [3]. This investigation should turn out to be helpful in the development of e cient correlation models for larger systems. Neutral neon is a well-known benchmark example for testing many-body approaches. In the present work, we apply the LCFI method to the study of the three lowest terms 2p6 1S, 2p53s 3Po and 2p53s 1Po of neutral neon. We investigate the convergence pattern of the total energy, speci c mass shift and hyper ne structure parameters for the three considered states. These properties are computed for monitoring the quality of the total polyelectronic wave functions. We present the contribution of each LCF function on the di erent properties, and additionally discuss the multi-reference models adopted for reaching simultaneously good total and transition energies. A comparison between the results obtained with ATSP2K [4] and GRASP2K [5] should shed some light on the importance of the relativistic e ects on each LCF function.
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| 10. |
- Verdebout, Simon, et al.
(författare)
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Hyperfine structures and Landé gJ-factors for n = 2 states in beryllium-, boron-, carbon-, and nitrogen-like ions from relativistic configuration interaction calculations
- 2014
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Ingår i: Atomic Data and Nuclear Data Tables. - : Elsevier. - 0092-640X .- 1090-2090. ; 100:5, s. 1111-1155
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Tidskriftsartikel (refereegranskat)abstract
- Energy levels, hyperfine interaction constants, and Landé gJ -factors are reported for n = 2 states in beryllium-, boron-, carbon-, and nitrogen-like ions from relativistic configuration interaction calculations. Valence, core–valence, and core–core correlation effects are taken into account through single and doubleexcitations from multireference expansions to increasing sets of active orbitals. A systematic comparison of the calculated hyperfine interaction constants is made with values from the available literature.
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