| 1. |
- Brage, Tomas, et al.
(författare)
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Effects of Core-valence and Core-core Correlation On the Line-strength of the Resonance Lines In Li-i and Na-i
- 1994
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Ingår i: Physical Review A (Atomic, Molecular and Optical Physics). - 1050-2947. ; 49:3, s. 2181-2184
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Tidskriftsartikel (refereegranskat)abstract
- The resonance lines in Li I and Na I both exhibit a puzzling discrepancy between experiment and accurate ab initio calculations. Only results from a semiempirical method, that in principal neglects core-core correlation, agree with the experiments. The agreement with a multiconfiguration Hartree-Fock calculation, including only core-valence correlation, shows that this might be fortuitous. A method for including some core-core correlation is designed and gives results in excellent agreement with other accurate ab initio methods.
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| 2. |
- Jönsson, Per, et al.
(författare)
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A Program For Computing Magnetic Dipole and Electric Quadrupole Hyperfine Constants From Mchf Wave-functions
- 1993
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Ingår i: Computer Physics Communications. - : Elsevier BV. - 0010-4655. ; 74:3, s. 399-414
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Tidskriftsartikel (refereegranskat)abstract
- Given an electronic wave function, generated by the MCHF program (LS format) or the MCHF_CI program (LSJ format), this program computes the hyperfine interaction constants, A(J) and B(J). In strong experimental magnetic fields, the splitting is also affected by the off-diagonal hyperfine constants A(J,J-1), B(J,J-1), and B(J,J-2) and these are computed as well, depending on the input data.
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| 3. |
- Jönsson, Per, et al.
(författare)
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Accurate Calculation of the Isotope Shift and Hyperfine-structure In the Boron (b-ii) Line At 1362 Angstrom
- 1994
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Ingår i: Astrophysical Journal. - : American Astronomical Society. - 0004-637X .- 1538-4357. ; 429:1
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Tidskriftsartikel (refereegranskat)abstract
- An extensive multiconfiguration Hartree-Fock (MCHF) calculation of the isotope shift and hyperfine structure in the resonance line of B II at 1362 angstrom has been performed. The calculated B-11-B-10 isotope shift is 13.3 mangstrom with an estimated uncertainty of 1%. The calculated interaction constants A and B give a hyperfine structure splitting of less than 0.45 mangstrom for both isotopes. The size of the isotope shift in the B II line is similar to the limit of detection in high-resolution observations with the Goddard High Resolution Spectrograph aboard the Hubble Space Telescope when side A becomes operational after the service mission.
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| 4. |
- Jönsson, Per, et al.
(författare)
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Large-scale Multiconfiguration Hartree-fock and Configuration-interaction Calculations of Isotope Shifts and Hyperfine Structures In Boron
- 1994
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Ingår i: Physical Review A (Atomic, Molecular and Optical Physics). - 1050-2947. ; 50:4, s. 3080-3088
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Tidskriftsartikel (refereegranskat)abstract
- A new isotope shift program, part of the multiconfiguration Hartree-Fock (MCHF) atomic structure package, has been written and tested. The program calculates the isotope shift of an atomic level from MCHF or configuration-interaction (CI) wave functions. The program is specially designed to be used with very large CI expansions, for which angular data cannot be stored on disk. To explore the capacity of the program, large-scale isotope shift calculations were performed for the 1s(2)2s(2)2p 2P, 1s(2)2s(2)3s2S, and 1s(2)2s2p2 2D levels in boron. From the isotope shifts of these levels the transition isotope shifts were calculated for the two resonance transitions. The calculated transition isotope shifts are in very good agreement with experimental shifts. As an additional test of the quality of the CI wave functions, the hyperfine structure was calculated for all levels.
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| 5. |
- Jönsson, Per, et al.
(författare)
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Large-scale Multiconfiguration Hartree-fock Calculations of Hyperfine-interaction Constants For Low-lying States In Beryllium, Boron, and Carbon
- 1993
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Ingår i: Physical Review A (Atomic, Molecular and Optical Physics). - 1050-2947. ; 48:6, s. 4113-4123
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Tidskriftsartikel (refereegranskat)abstract
- Multiconfiguration Hartree-Fock (MCHF) calculations of hyperfine constants for the 2s2p 3P states of beryllium and the ground states of boron and carbon are reported. The capacity of a recently developed configuration-interaction program [Froese Fischer and Tong (unpublished); Stathopoulos and Froese Fischer (unpublished)], allowing for large configuration expansions, is explored. Using a systematic active-space MCHF approach, combined with large multireference configuration-interaction calculations, it is shown that hyperfine constants can be calculated very accurately. To reliably account for spin-polarization of the Is and 2s shells in boron and carbon, three-particle effects had to be included in a systematic way. The relativistic, finite-nuclear-size- and finite-nuclear-mass-corrected values of the hyperfine constants are compared with experimental values and with the most accurate theoretical values obtained with other methods.
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| 6. |
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| 7. |
- Tong, M, et al.
(författare)
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Convergence studies of atomic properties from variational methods: total energy, ionization energy, specific mass shift, and hyperfine parameters for Li
- 1993
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Ingår i: Physica Scripta. - : IOP Publishing. - 0031-8949 .- 1402-4896. ; 48:4, s. 446-453
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Tidskriftsartikel (refereegranskat)abstract
- Systematic variational calculations using the multi-configuration Hartree-Fock method for Li are reported. For 1 s 2 2 s 2 S of Li, an nl -expansion is attempted in configuration space, similar to a partial wave expansion for helium-like systems. The total energy, ionization energy, specific mass shift, and hyperfine contact term are calculated with respect to increasing size of the configuration set. A comparison is made with n -expansion in configuration space, which is found to be the more efficient method. The total energy obtained from our variational procedure is lower than that of a previously reported partial wave study on ground state of Li. Similar n -expansion studies are performed for 1 s 2 2 p 2 P . For the latter, the 2 s -2 p transition integrals are reported, showing convergence of the transition energy as well as the length and velocity form of the f -value.
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