1. 
 Bengtsson, Peter, et al.
(författare)

Energy structure and transition rates in the Nelike sequence from relativistic CI calculations
 2012

Ingår i: Europhysics Conference Abstracts.  European Physical Society.  2914771754 ; :36C

Annan publikation (populärvet., debatt m.m.)abstract
 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 BreitPauli approximation, the fully relativistic GRASP2K code can be used. GRASP2K is based on the multiconfiguration DiracHartreeFock method and implements a biorthogonal 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 offdiagonal hyperfine interaction constants, isotope shifts, Land´e gJ factors, and splittings of magnetic substate in intermediate and strong magnetic fields. In this work, GRASP2K has been applied to provide highly accurate spectroscopic data for ions in the Nelike sequence between Mg III and Kr XXVII. Valence, corevalence, and corecore correlation effects were accounted for through SDMR 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 beamfoil measurements as well as from accurate MCHF BreitPauli calculations.


2. 
 Jönsson, Per, et al.
(författare)

Relativistic CI Calculations of Spectroscopic Data for the 2p(6) and 2p(5)3l Configurations in Nelika Ions between Mg III and Kr XXVII
 2011

Rapport (övrigt vetenskapligt)abstract
 Energies, E1, M1, E2, M2 transition rates, oscillator strengths, and lifetimes from relativistic configuration interaction calculations are reported for the states of the 2p6, 2p53s, 2p53p, and 2p53d, configurations in all Nelike ions between Mg III and Kr XXVII. Corevalence and corecore correlation effects are accounted for through SDexpansions to increasing sets of active orbitals. The Breit interaction and leading QED effects are included as perturbations. The results are compared with experiments and other recent benchmark calculations. 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%.


3. 
 Jönsson, Per, et al.
(författare)

Relativistic CI calculations of spectroscopic data for the 2p6 and 2p53l configurations in Nelike ions between Mg III and Kr XXVII
 2014

Ingår i: Atomic Data and Nuclear Data Tables.  Elsevier.  0092640X. ; 100:1, s. 1154

Tidskriftsartikel (refereegranskat)abstract
 Energies, E1, M1, E2, M2 transition rates, oscillator strengths, and lifetimes from relativistic configuration interaction calculations are reported for the states of the 2p6, 2p53s, 2p53p, and 2p53d, configurations in all Nelike ions between Mg III and Kr XXVII. Core–valence and core–core correlation effects are accounted for through single and double excitations to increasing sets of active orbitals. The Breit interaction and leading quantum electrodynamic effects are included as perturbations. The results are compared with experiments and other recent benchmark calculations. 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%.


4. 
 Jönsson, Per, et al.
(författare)

Transition rates in the B, C, N, O, and Nelike sequences from relativistic CI calculations
 2011

Ingår i: Abstracts 43rd Conference of the European Group for Atomic Systems (EGAS).  European Physical Society.

Konferensbidrag (övrigt vetenskapligt)abstract
 Atomic data are important in astrophysical applications and transition data can be used in the determination of element abundances and plasma diagnostics [1]. 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 BreitPauli approximation, the fully relativistic GRASP2K code [2] can be used. GRASP2K is based on the multicon guration DiracHartreeFock method and implements a biorthogonal transformation method that permits initial and nal states in a transition array to be optimized separately, which, in many cases, leads to more accurate values of the resulting rates [3]. The GRASP2K package also contains modules to compute diagonal and o diagonal hyper ne interaction constants, isotope shifts, Land e gJ factors, and splittings of magnetic substate in intermediate and strong magnetic elds. In this work, GRASP2K has been applied to provide highly accurate spectroscopic data for transitions in the B, C, N, O, and Nelike sequences [4]. Valence, corevalence, and corecore correlation e ects were accounted for through SDMR expansions to increasing sets of active orbitals. The calculated energy levels generally agree to within a few hundred cm with the experimentally compiled results. Babushkin (length) and Coulomb (velocity) forms of transition rates di er with less than 1% for the majority of the allowed transitions. The perspectives of massive data production on parallel clusters to cover the needs of the astrophysical community is discussed.

