Effective collision strengths for optically allowed transitions among degenerate levels of hydrogenic ions with

Atomic Data and Nuclear Data Tables

Bogdanovich

Karpuškienė

et al. 2016

Self Cite

We report calculations of energy levels and radiative rates (A-values) for transitions in Cr-like Co IV and Ni V. The quasirelativistic Hartree-Fock (QRHF) code is adopted for calculating the data although grasp (general-purpose relativistic atomic structure package) and flexible atomic code (fac) have also been employed for comparison purposes. No radiative rates are available in the literature to compare with our results, but our calculated energies are in close agreement with those compiled by NIST for a majority of the levels. However, there are discrepancies for a few levels of up to 3%. TheA-values are listed for all significantly contributing E1, E2 and M1 transitions, and the corresponding lifetimes reported, although unfortunately no previous theoretical or experimental results exist to compare with our data.

Section: Introductionsupporting

confidence: 68%

Energy levels and radiative rates for transitions in Cr-like Co IV and Ni V

Atomic Data and Nuclear Data Tables

Bogdanovich

Karpuškienė

et al. 2016

Self Cite

“…Although both darc and fac include the contribution of higher neglected partial waves from the Coulomb-Bethe formulation of Burgess et al [11], differences in values of Ω can sometimes be appreciable. Therefore, to resolve the discrepancies between the fac and darc calculations, and to determine values of Ω as accurately as possible, we have performed yet another calculation using a combination of the close-coupling (CC) and Coulomb-Born (CB) programs, described fully by Igarashi et al [12,13], and Hamada et al [14]. These calculations are similar to those for elastic transitions in Al XIII [15], Ar XVIII [10] and Fe XXVI [9].…”

Section: Methods Of Calculationsmentioning

confidence: 99%

“…Comparison of collision strengths for the[14][15] (4d 2 D 5/2 -4f 2 F o 5/2 ), 21-22 (5f 2 F o 5/2 -5d 2 D 5/2 ) and 23-24 (5g 2 G 7/2 -5f 2 F o 7/2) transitions of He II. Broken curves are from the CC+CB programs, and the Ω from FAC are shown as, squares: 14-15, circles: 21-22 and stars: 23-24 transition.…”

mentioning

confidence: 99%

Radiative Rates and Electron Impact Excitation Rates for Transitions in He II

Igarashi

Keenan

et al. 2017

Atoms

Abstract:We report calculations of energy levels, radiative rates, collision strengths and effective collision strengths for transitions among the lowest 25 levels of the n ≤ 5 configurations of He II. The general-purpose relativistic atomic structure package (GRASP) and Dirac atomic R-matrix code (DARC) are adopted for the calculations. Radiative rates, oscillator strengths and line strengths are reported for all electric dipole (E1), magnetic dipole (M1), electric quadrupole (E2) and magnetic quadrupole (M2) transitions among the 25 levels. Furthermore, collision strengths and effective collision strengths are listed for all 300 transitions among the above 25 levels over a wide energy (temperature) range up to 9 Ryd (10 5.4 K). Comparisons are made with earlier available results, and the accuracy of the data is assessed.

“…However, sometimes their significance is appreciable even for lighter ions, as shown by Aggarwal et al [20]. Particularly important is their contribution in splitting the fine-structure levels of a term -see, for example, Hamada et al [21] for energy levels of H-like ions. Finally, for most of the lighter ions (Z ≤ 20) inclusion of one-body relativistic operators, in a Breit-Pauli approximation, is sufficient as noted by [22], but for heavier ions fully relativistic calculations are preferable [1], [19].…”

Section: Choices For a Model Calculationmentioning

confidence: 99%

Assessment of Atomic Data: Problems and Solutions

Fusion Science and Technology

Keenan

2013

For the reliable analysis and modelling of astrophysical, laser-produced and fusion plasmas, atomic data are required for a number of parameters, including energy levels, radiative rates and electron impact excitation rates. Such data are desired for a range of elements (H to W) and their many ions. However, measurements of atomic data, mainly for radiative and excitation rates, are not feasible for many species and therefore calculations are needed. For some ions (such as of C, Fe and Kr) there are a variety of calculations available in the literature, but often they significantly differ from one another. Therefore, there is a great demand from the user community to have data 'assessed' for accuracy so that they can be confidently applied to the modelling of plasmas. In this paper we highlight the difficulties in assessing atomic data and offer some solutions for improving the accuracy of calculated results.