Background We present the first electron-impact excitation of Be-like Mg calculated using the R-matrix theory. Previous excitation rates for the n=2 complex were obtained by Keenan et al. (1986) by interpolation along the sequence of the rates calculated with the R-
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Electron-impact excitation of Be-like Mg
G.Del Zanna1,2, I. Rozum1, N. R. Badnell3
1 Mullard Space Science Laboratory, University College London, UK
2 DAMTP, Centre for Mathematical Sciences, University of Cambridge, UK
3 Department of Physics, University of Strathclyde, UK
T h e o r y
- electron-electron correlation
- (N+1)-e- collision complex is similar to a bound state
- multicentre expansionof the target wavefunction
- exchange and correlation are negligible
- single centre expansion of the target wavefunction
The total N+1 wavefunction can be expanded in a close-coupling form:
Ψ(x1…xN+1) = ∑ Φi(x1…xN; rN+1σN+1) rN+1-1 Fi (rN+1)
where Φ is a set of channel functions, F is the reduced radial wavefunction.
Comparison with a solar observation
Bhatia,A.K., Landi, E., 2007, ADNDT 93,742
Chidichimo,M. C., Del Zanna, G.,Mason, H.E., Badnell,N. R., Tully, J.A., Berrington, K.A., 2005, A&A,430,331
Feldman, U., Doschek, G. A., Sch¨uhle, U., & Wilhelm, K. 1999, ApJ, 518, 500
Keenan, F. P., Berrington, K. A., Burke, P. G., Dufton, P. L., & Kingston, A. E. 1986, Phys. Scr, 34, 216
Sampson, D.H., Goett, S.J., Clark, R.E.H, 1984, ADNDT, 30, 125
Emissivity ratio curves of a SOHO/SUMER off-limb spectrum of the quiet solar corona (Feldman et al.
1999). The crossing of the intercombination with the 1P1– 1D2 line indicates a temperature of
1.4 MK with the present calculations, in good agreement with the independent measurement of
1.35 MK by Feldman et al. (1999). The CHIANTI model indicates a lower temperature of 1 MK.
Support from STFC is acknowledged (GDZ: Advanced Fellowship and APAP network; NRB: APAP network