Atomic data from the IRON Project. LXV. Electronimpact excitation of Fe^{6+}
Abstract
We present Rmatrix results for the electronimpact excitation of Fe^{6+}. The intermediatecoupling frame transformation (ICFT) method has been used to obtain levelresolved collision strengths. We then calculate effective collision strengths assuming a Maxwellian distribution for the incident electron velocities. A large configuration interaction (CI) expansion of 1896 LS terms (4776 finestructure levels) is used to obtain an accurate target. This is reduced to 89 closecoupling (CC) terms (189 levels) for the scattering calculation. To investigate the importance of CI, we also perform a second calculation with the same CC expansion but a smaller CI expansion. We discuss the difficulties of such a comparison and look at which transitions show the most sensitivity to the CI expansion. Our effective collision strengths are compared with a previous IRON Project report (Berrington et al. 2000, A&A, 142, 313) for transitions within the ground configuration and a recent distorted wave calculation (Zeng et al. 2005, MNRAS, 357, 440) for transitions to excited configurations. We find good agreement with the results of the previous Rmatrix calculation and with the hightemperature distortedwave results for most transitions, although there are some significant differences at lower temperatures in the latter case.
 Publication:

Astronomy and Astrophysics
 Pub Date:
 April 2008
 DOI:
 10.1051/00046361:20079073
 Bibcode:
 2008A&A...481..543W
 Keywords:

 atomic data