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Astron. Astrophys. Suppl. Ser. 142, 313-316

Atomic data from the IRON Project

XLI. Electron excitation rates among the 3d2 fine-structure levels of Ca-like Fe VII

K.A. Berrington1 - S. Nakazaki2 - P.H. Norrington3

1 - School of Science & Mathematics, Sheffield Hallam University, Sheffield S1 1WB, UK
2 - Department of Materials Science, Faculty of Engineering, Miyazaki University, Miyazaki 889-21, Japan
3 - Department of Applied Mathematics & Theoretical Physics, Queen's University, Belfast BT7 1NN, UK

Received July 30; accepted October 22, 1999


Electron excitation collision strengths of 3d2fine-structure transitions in Ca-like Fe VII are calculated using an R-matrix method, which included the 80 terms arising from the 3d2, 3d4s, 3d4p, 3d4d, 3d4f and 3p53d3 configurations. Extensive autoionizing resonance structures together with channel coupling is therefore explicitly included; relativistic effects are accounted for by a term-coupling transformation. A thermal average is taken to obtain the effective fine-structure collision strength as a function of electron temperature T, for log T(K) = 4.3-6. Open 3p-shell resonances are seen to considerably enhance the background collision strength, by several factors for some of the 3d $^{2}_{j\rightarrow j'}$ transitions.

Key words: atomic data

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