R-matrix electron-impact excitation data for the Ne-like iso-electronic sequence

Abstract

We present results for the electron-impact excitation of all Ne-like ions from Na + to Kr 26+ obtained using the intermediate-coupling frame transformation R-matrix approach. For each ion's calculation, the close-coupling expansion is taken to be the 113 LS terms (209 levels) belonging to the configurations [1s 2 ]2s 2 2p 6 , 2s 2 2p 5 {3, 4, 5}l, 2s2p 6 {3, 4, 5}l (l ∈ s, p, d, f, and g), and 2s 2 2p 5 {6, 7}l (l ∈ s, p, and d). An additional configuration interaction effect arising from configurations of 2s 2 2p 4 3l{3, 4, 5}l (l ∈ s, p, d, f and g) was included in the target expansion. A detailed comparison of the target structure has been made for six specific ions (Si 4+ , Ar 8+ , Ca 10+ , Fe 16+ , Ni 18+ , and Kr 26+ ) spanning the sequence to assess the accuracy for the entire sequence. Effective collision strengths (Υs) are presented at temperatures ranging from 2×10 2 (q+1) 2 K to 2×10 6 (q+1) 2 K (where q is the residual charge of ions, i.e. Z −10). Detailed comparisons for the Υs are made with the results of previous calculations for several ions, which span the sequence. Furthermore, we examine the iso-electronic trends of effective collision strengths as a function of temperature. The present results are the only R-matrix ones for the majority of the ions and the most extensive and complete data for modelling to-date.

CHIANTI – An atomic database for emission lines. Version 8

“…As in the case of the Li-like ions mentioned above, some of the collision strengths calculated by Liang & Badnell (2010) were affected by a minor error which only affected the hightemperature rates. We used the corrected data (as obtained from the authors) for Mg iii, P vi, Mn xvi, Si v, S vii, Ar ix, and Ni xix.…”

“…These calculations represent a significant improvement over the few previous calculations along the sequence. In general, we have adopted the Liang & Badnell (2010) energies, A-values and collision strengths. To reduce the size of the data files containing the radiative rates, we have retained for all the new datasets only transitions with an A-value greater than 10 −5 the largest A-value (for each level).…”

“…For the astrophysically important ions Mg iii, Al iv, Si v, S vii, Ar ix, Ca xi, and Ni xix we have replaced the Liang & Badnell (2010) A-values of the transitions among the 2p 6 and 2p 5 3l configurations (lowest 27 levels) with the results of the MCDHF calculations obtained by Jönsson et al (2014) with the GRASP2K code (Jönsson et al 2007). For some ions, the ordering of the levels was different, as well as the LSJ designation …”

Atomic data for astrophysics: Fe IX

“…We note that there is an extended literature where the results of the ICFT and BPRM methods are compared. For example, the original works by Griffin et al (1998) for Mg-like ions, and Badnell & Griffin (1999) for Ni v. More recently, Liang & Badnell (2010) carried out extensive comparisons between ICFT and DARC for for Fe xvi. No significant differences between the results of the two methods have been found.…”

Validation of Spectroscopic Model for Fe Ions in Non-Equilibrium Ionization Plasma in LHD and Hinode

“…ADAS contains various atomic datasets for one ion; for comparison, we selected three different atomic datasets for energy levels, transition probabilities, and electron-impact excitation effective collision strengths. Specifically, the selected datasets were "chv6" whose atomic data are taken from CHIANTI ver.6 (245 levels) [29], "cpb06" whose excitation effective collision strengths are obtained by the Dirac-Fock R-matrix method (139 levels) [30], and "lgy09" whose excitation effective collision strengths are obtained by the ICFT Rmatrix method (209 levels) [31]. In the CHIANTI dataset, electron-impact excitation rate coefficients are calculated by the distorted wave method and are included only for certain selected transitions.…”