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

2018 ◽  
Vol 96 (10) ◽  
pp. 1155-1157 ◽  
Author(s):  
Kanti M. Aggarwal
Keyword(s):  
R Matrix ◽  
Collision Strength ◽  
Effective Collision

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.

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

2018 ◽  
Vol 96 (10) ◽  
pp. 1158-1161 ◽  
Author(s):  
Kanti M. Aggarwal
Keyword(s):  
R Matrix ◽  
Collision Strength ◽  
Effective Collision

In a recent paper, Goyal et al. [Can. J. Phys. 95, 1127 (2017)] have reported results for collision strengths (Ω) and effective collision strengths (ϒ) for transitions among the lowest 52 levels of F-like Br XXVII. For their calculations, they have adopted the Dirac atomic R-matrix code (DARC) and the flexible atomic code (FAC). In this comment we demonstrate that their results for both parameters are erratic, inaccurate, and unreliable.

Collision strength and effective collision strength for Br XXVII

2017 ◽  
Vol 95 (11) ◽  
pp. 1127-1135 ◽  
Author(s):  
Arun Goyal ◽  
Rinku Sharma ◽  
Indu Khatri ◽  
A.K. Singh ◽  
Shougaijm Somorendro Singh ◽  
...  
Keyword(s):  
Fine Structure ◽  
Plasma Diagnostics ◽  
Threshold Region ◽  
Wave Method ◽  
Distorted Wave ◽  
R Matrix ◽  
Collision Strength ◽  
Forbidden Transitions ◽  
Distorted Wave Method ◽  
Effective Collision

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.

Collision strength and effective collision strength for Ba XLVIII

2017 ◽  
Vol 95 (2) ◽  
pp. 173-178 ◽  
Author(s):  
Man Mohan ◽  
Arun Goyal ◽  
Indu Khatri ◽  
Shougaijm Somorendro Singh ◽  
A.K. Singh
Keyword(s):  
Plasma Diagnostics ◽  
Ground State ◽  
Threshold Region ◽  
Wave Method ◽  
Distorted Wave ◽  
R Matrix ◽  
Collision Strength ◽  
Forbidden Transitions ◽  
Distorted Wave Method ◽  
Effective Collision

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.

scholarly journals Dirac R-matrix collision strengths and effective collision strengths for transitions of Ni xvii

2011 ◽  
Vol 537 ◽  
pp. A12 ◽  
Author(s):  
C. E. Hudson ◽  
P. H. Norrington ◽  
C. A. Ramsbottom ◽  
M. P. Scott
Keyword(s):  
R Matrix ◽  
Effective Collision

scholarly journals Collisional Excitation of Fluorine Like Tungsten using Relativistic Dirac Atomic R-matrix Method

2015 ◽  
Vol 2 (1) ◽  
pp. 1-14
Author(s):  
Arun Goyal ◽  
Indu Khatri ◽  
Sunny Aggarwal ◽  
A. K. Singh ◽  
Rinku Sharma ◽  
...  
Keyword(s):  
Fine Structure ◽  
Energy Levels ◽  
Impact Excitation ◽  
Electron Impact Excitation ◽  
Collisional Excitation ◽  
Distorted Wave ◽  
Fusion Plasma ◽  
R Matrix ◽  
Target States ◽  
Effective Collision

We report the new extensive calculations for collision strengths and effective collision strengths of Electron impact excitation of fine structure transitions in F-like W using fully relativistic Dirac Atomic R-matrix Code. We have included all 113 target states which belong to 2s22p5, 2s2p6, 2s22p43l, 2s2p53l, 2p63l configurations. The convergence of reported collision strengths is tested by performingthe same calculations for lesser number of target states which verify the individuality of our results.Effective collision strengthsover a wide temperature range 104-107K are computed. Further, to assess the accuracy and authenticity of our target states energies, a similar parallel calculation has also been performed using a fully relativistic distorted wave (RDW) method and a comparison of energy levels with NIST, FAC and other experimental observations has been made. We believe that the collision strength results for all forbidden transitions within the 113 fine structure levels, presented in this paper will play a substantial role in fusion plasma diagnostics.

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

2020 ◽  
Vol 98 (5) ◽  
pp. 497-497
Author(s):  
Man Mohan ◽  
Arun Goyal ◽  
Indu Khatri
Keyword(s):  
Collision Strength ◽  
Incorrect Conclusion ◽  
Effective Collision

We show that the comment of K.M. Aggarwal (2018, Can. J. Phys. 96(10), doi: https://www.nrcresearchpress.com/doi/pdf/10.1139/cjp-2017-0842 ), although being only marginally relevant to the content of the original paper (2017, Can. J. Phys. 95(2), doi: https://www.nrcresearchpress.com/doi/pdf/10.1139/cjp-2016-0513 ), misinterprets our results and leads to an incorrect conclusion.

scholarly journals Effective collision strengths for electron-impact excitation of Al10+

2006 ◽  
Vol 24 (2) ◽  
pp. 235-240 ◽  
Author(s):  
V. STANCALIE ◽  
V. PAIS
Keyword(s):  
Electron Impact ◽  
Maximum Energy ◽  
Impact Excitation ◽  
Electron Collision ◽  
Electron Impact Excitation ◽  
Coupling Scheme ◽  
Close Coupling ◽  
R Matrix ◽  
Intermediate Coupling Scheme ◽  
Effective Collision

Electron collision strengths for electron-impact excitation of Li-like and Al ion are evaluated in close-coupling approximation using the multi-channel R-matrix method. Five LS target eigenstates are included in the expansion of the total wave function, consisting of the twon= 2 states withconfigurationsof 1s22s, 1s22p, and threen= 3 states withconfigurations1s23s, 1s23p, and 1s23d. Collision strengths are obtained in LS coupling using FARM code and in intermediate coupling scheme using the SUPERSTRUCTURE program. The effective collision strengths are calculated as function of temperature, up to a temperature that does not exceed half of the maximum energy in the R-matrix run.

scholarly journals Electron-impact fine-structure excitation of Fe ii at low temperature

2019 ◽  
Vol 485 (2) ◽  
pp. 2252-2258
Author(s):  
Yier Wan ◽  
C Favreau ◽  
S D Loch ◽  
B M McLaughlin ◽  
Yueying Qi ◽  
...  
Keyword(s):  
Fine Structure ◽  
Low Temperature ◽  
Electron Impact ◽  
Rate Coefficients ◽  
Atomic Data ◽  
Ground Term ◽  
R Matrix ◽  
Uncertainty Estimates ◽  
Frame Transformation ◽  
Effective Collision

Abstract Fe ii emission lines are observed from nearly all classes of astronomical objects over a wide spectral range from the infrared to the ultraviolet. To meaningfully interpret these lines, reliable atomic data are necessary. In the work presented here we focused on low-lying fine-structure transitions, within the ground term, due to electron impact. We provide effective collision strengths together with estimated uncertainties as functions of temperature of astrophysical importance (10−100 000 K). Due to the importance of fine-structure transitions within the ground term, the focus of this work is on obtaining accurate rate coefficients at the lower end of this temperature range, for applications in low-temperature environments such as the interstellar medium. We performed three different flavours of scattering calculations: (i) an intermediate coupling frame transformation (icft) R-matrix method, (ii) a Breit–Pauli R-matrix (bprm) method, and (iii) a Dirac Atomic R-matrix Code (darc). The icft and bprm calculations involved three different autostructure target models each. The darc calculation was based on a reliable 20 configuration, 6069 level atomic structure model. Good agreement was found with our bprm and darc collision results compared to previous R-matrix calculations. We present a set of recommended effective collision strengths for the low-lying forbidden transitions together with associated uncertainty estimates.

scholarly journals Atomic Data Assessment with PyNeb

Atoms ◽  
2020 ◽  
Vol 8 (4) ◽  
pp. 66
Author(s):  
Christophe Morisset ◽  
Valentina Luridiana ◽  
Jorge García-Rojas ◽  
Verónica Gómez-Llanos ◽  
Manuel Bautista ◽  
...  
Keyword(s):  
Atomic Data ◽  
Collision Strength ◽  
Gaseous Nebulae ◽  
Data Assessment ◽  
Ngc 7027 ◽  
Temperature Diagnostics ◽  
The Impact ◽  
Effective Collision ◽  
Space Line ◽  
Python Package

PyNeb is a Python package widely used to model emission lines in gaseous nebulae. We take advantage of its object-oriented architecture, class methods, and historical atomic database to structure a practical environment for atomic data assessment. Our aim is to reduce the uncertainties in the parameter space (line ratio diagnostics, electron density and temperature, and ionic abundances) arising from the underlying atomic data by critically selecting the PyNeb default datasets. We evaluate the questioned radiative-rate accuracy of the collisionally excited forbidden lines of the N- and P-like ions (O ii, Ne iv, S ii, Cl iii, and Ar iv), which are used as density diagnostics. With the aid of observed line ratios in the dense NGC 7027 planetary nebula and careful data analysis, we arrive at emissivity ratio uncertainties from the radiative rates within 10%, a considerable improvement over a previously predicted 50%. We also examine the accuracy of an extensive dataset of electron-impact effective collision strengths for the carbon isoelectronic sequence recently published. By estimating the impact of the new data on the pivotal [N ii] and [O iii] temperature diagnostics and by benchmarking the collision strength with a measured resonance position, we question their usefulness in nebular modeling. We confirm that the effective-collision-strength scatter of selected datasets for these two ions does not lead to uncertainties in the temperature diagnostics larger than 10%.

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