Validity of the ICFT R-matrix method : Be-like Al 9+ a case study

Fernández-Menchero, L. and Del Zanna, G. and Badnell, Nigel (2015) Validity of the ICFT R-matrix method : Be-like Al 9+ a case study. Monthly Notices of the Royal Astronomical Society, 450 (4). pp. 4174-4183. ISSN 0035-8711 (https://doi.org/10.1093/mnras/stv887)

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Abstract

We have carried out 98-level configuration-interaction/close-coupling (CI/CC) intermediate coupling frame transformation (ICFT) and Breit–Pauli R-matrix calculations for the electron-impact excitation of Be-like Al 9+. The close agreement that we find between the two sets of effective collision strengths demonstrates the continued robustness of the ICFT method. On the other hand, a comparison of this data with previous 238-level CI/CC ICFT effective collision strengths shows that the results for excitation up to n = 4 levels are systematically and increasingly underestimated over a wide range of temperatures by R-matrix calculations whose CC expansion extends only to n = 4 (98-levels). Thus, we find to be false a recent conjecture that the ICFT approach may not be completely robust. The conjecture was based upon a comparison of 98-level CI/CC Dirac R-matrix effective collision strengths for Al 9+ with those from the 238-level CI/CC ICFT R-matrix calculations. The disagreement found recently is due to a lack of convergence of the CC expansion in the 98-level CI/CC Dirac work. The earlier 238-level CI/CC ICFT work has a superior target to the 98-level CI/CC Dirac one and provides more accurate atomic data. Similar considerations need to be made for other Be-like ions and for other sequences.

  • Item type:Article
    ID code:53097
    Dates:
    Date
    Event
    11 July 2015
    Published
    20 May 2015
    Published Online
    Notes:This is a pre-copyedited, author-produced PDF of an article accepted for publication in Monthly Notices of the Royal Astronomical Society following peer review. The version of record Fernández-Menchero, L., Del Zanna, G., & Badnell, N. (2015). Validity of the ICFT R-matrix method: Be-like Al 9+ a case study . Monthly Notices of the Royal Astronomical Society, 450(4), 4174-4183. is available online at: http://mnras.oxfordjournals.org/content/450/4/4174.abstract
    Subjects:Science > Physics
    Science > Astronomy
    Department:Faculty of Science > Physics
    Depositing user: Pure Administrator
    Date deposited:26 May 2015 15:12
    Last modified:11 Apr 2024 00:54
    Related URLs:
    URI:https://strathprints.strath.ac.uk/id/eprint/53097
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