Collision strength and effective collision strength for Ba XLVIII

Abstract

Collision strengths for the lowest 52 fine-structure levels of Ba XLVIII 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. Effective collision strengths have also been determined within a temperature range from the ground state. Collision strengths from ground state have also been computed with the relativistic distorted wave method, the flexible atomic code (FAC) was used for checking 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.

Reply to the comment by K.M. Aggarwal on “Collision strength and effective collision strength for Ba XLVIII”

“…The reason for the anomalous behaviour of ϒ results by Mohan et al [1], particularly at lower temperatures, is not difficult to diagnose. This is primarily due to their choice of energy mesh (␦E) for the resolution of resonances and the determination of ϒ.…”

“…Another example for the incorrect ϒ results of Mohan et al [1] is the 1-3 transition (i.e., 2s 2 2p 5 2 P 3/2 o -2s2p 6 2 S 1/2 ), for which they have shown ⍀ in their Fig. 2.…”

“…For the construction of wavefunctions, Mohan et al [1] adopted the general-purpose relativistic atomic structure package (GRASP). Several versions of this code are currently in use by many workers, but the one adopted by them is the original one (i.e., GRASP0), but considerably modified by P.H.…”

“…For the calculations of ⍀, Mohan et al [1] adopted the DARC code, included a wide range of partial waves with angular momentum J ≤ 41, considered a wide range of energy (up to 1000 Ryd), and resolved resonances to determine ϒ at temperatures below 10 6 K. For our calculations, the FAC is employed, which is based on distorted-wave (DW) approximation, and generally provides results of ⍀ comparable to R-matrix, as may also be noted from Table 2 of [1]. Similarly, the energies obtained with this code are comparable with those of Mohan et al, and there are no appreciable discrepancies, in magnitude or orderings, for any levelsee also Table 1 of [1]. For this reason we are not listing our energy levels for Ba XLVIII.…”

“…In a recent paper, Mohan et al [1] have reported results for collision strengths (⍀) and effective collision strengths (ϒ) for transitions from the 2s 2 2p 5 2 P 3/2 o ground to 51 excited levels of F-like Ba XLVIII, which belong to the 2s 2 2p 5 , 2s2p 6 , and 2s 2 2p 4 3ℓ configurations. For the calculations of ⍀, they have adopted two independent codes, namely, the Dirac atomic R-matrix code (DARC) and the flexible atomic code (FAC).…”