Comment on “Collision strength and effective collision strength for Ba XLVIII” by Mohan et al. [Can. J. Phys. 95, 173 (2017)]

Abstract

In a recent paper, Mohan et al. [Can. J. Phys. 95, 173 (2017)] have reported results for collision strengths (Ω) and effective collision strengths (ϒ) for transitions from the ground to higher 51 excited levels of F-like Ba XLVIII. For the calculations of Ω, the Dirac atomic R-matrix code (DARC) and the flexible atomic code (FAC) have been adopted, to facilitate a direct comparison. However, for the subsequent calculations of ϒ, DARC alone has been employed. In this comment, we demonstrate that while their limited results for Ω are comparatively reliable, for ϒ they are not, particularly for the allowed transitions and at lower temperatures. Apart from the unexpected behaviour, their ϒ values are overestimated for several transitions, by about a factor of two.