Collision strength and effective collision strength for Br XXVII

Abstract

Collision strengths for all 1326 transitions among lowest 52 fine-structure levels of Br XXVII have been computed using Dirac atomic R-matrix code (DARC). Resonances in the threshold region have been completely resolved and the contributions of these resonances to allowed and forbidden transitions have been presented. The partial collision strength for each angular momentum has been studied graphically. Effective collision strengths have also been determined within the temperature range for all 1326 transitions among the lowest 52 levels. Target state energies of the lowest 52 fine-structure levels have been computed from the multi-configuration Dirac–Fock method (MCDF). Additionally, similar calculations with the relativistic distorted wave method and flexible atomic code (FAC) have also been performed to check the accuracy of our results. The present work represents a new and significant work with improvement in the field. We believe that our presented data of collision and effective collision strengths may be useful in the future for benchmark calculations and for plasma diagnostics.

Comment on “Collision strength and effective collision strength for Br XXVII” by Goyal et al. [Can. J. Phys. 95, 1127 (2017)]

“…Our level energies obtained with the GRASP and FAC codes are comparable with those reported by Goyal et al [1], and hence are not listed here. Anyway, our focus is on the calculations for Ω and Υ.…”

“…In Fig. 1, we show a comparison between the Ω obtained in our FAC calculations with those listed by Goyal et al [1] with DARC, for three allowed transitions, namely 4-14 (2s 1 of [1] for definition of all 52 levels. These transitions have been chosen because of their comparatively large magnitude, and allowed transitions are much easier to compare with because their Ω are strongly dependent on their oscillator strengths (f-values) and energy differences, i.e.…”

“…Not only Goyal et al [1] have performed their calculations in a very limited energy range, but their Ω results also show an incorrect behaviour as is clearly seen in Fig. 1.…”

“…In a recent paper, Goyal et al [1] have reported results for collision strengths (Ω) and effective collision strengths (Υ) for transitions among the lowest 52 levels of F-like Br XXVII. These levels belong to the 2s 2 2p 5 , 2s2p 6 , and 2s 2 2p 4 3 configurations.…”

“…For the calculations of Ω, and subsequently Υ, Goyal et al [1] have included 27 configurations in the construction of their wavefunctions, which belong to 2s 2 2p 5 , 2s2p 6 , 2p 6 3 , 2s 2 2p 4 3 , 2s2p 5 3 , 2s 2 2p 4 4 , 2s2p 5 4 , 2s 2 2p 4 5 , and 2s2p 5 5 , with ≤ f, and generate 431 levels in total. For these calculations, the GRASP0 version of the general-purpose relativistic atomic structure package of P.H.…”