EDP Sciences
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Volume 446, Number 3, February II 2006
Page(s) 1185 - 1190
Section Atomic, molecular and nuclear data
DOI http://dx.doi.org/10.1051/0004-6361:20053813
A&A 446, 1185-1190 (2006)
DOI: 10.1051/0004-6361:20053813

Electron collisions with Fe-peak elements: Fe IV

I. Forbidden transitions: 3d $\mathsf{^5}$ - 3d $\mathsf{^4}$4s and 3d $\mathsf{^5}$ - 3d $\mathsf{^4}$4p manifolds
B. M. McLaughlin1, A. Hibbert1, M. P. Scott1, C. J. Noble2, V. M. Burke2 and P. G. Burke1

1  School of Mathematics and Physics, Queen's University of Belfast, Belfast BT7 1NN, UK
    e-mail: b.mclaughlin@qub.ac.uk
2  Computational Science and Engineering Department, CCLRC Daresbury Laboratory, Keckwick Lane, Daresbury, Warrington WA4 4AD, UK

(Received 11 July 2005 / Accepted 26 September 2005 )

Electron-impact excitation collision strengths of the Fe-peak element Fe IV are calculated in the close-coupling approximation using the parallel R-matrix program PRMAT. One hundred and eight LS - coupled states arising from the $\rm 3d^5$, $\rm 3d^44s$ and $\rm 3d^44p$ configurations of Fe IV, are retained in the present calculations. Accurate multi-configuration target wavefunctions are employed with the aid of $\rm 3p^2 \rightarrow 3d^2$ electron promotions and a $\overline{\rm 4d}$ correlation orbital. The effective collision strengths required in the analysis of astrophysically important lines in the Fe IV spectra, are obtained by averaging the electron collision strengths for a wide range of incident electron energies, over a Maxwellian distribution of velocities. Results are tabulated for forbidden transitions between the $\rm 3d^5$, $\rm 3d^44s$ and the $\rm 3d^44p$ manifolds for electron temperatures ($T_{\rm e}$ in degrees Kelvin) in the range $3.3 \leq {\rm Log} \, T_{\rm e} \leq 6.0$ that are applicable to many laboratory and astrophysical plasmas. The present results provide new results for forbidden lines in the Fe IV spectrum studied here.

Key words: atomic data -- atomic processes

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