Radiative transition rates for the forbidden lines in Fe II^⋆

School of Mathematics and Physics, Queen’s University Belfast, Belfast BT7 1NN, Northern Ireland, UK
e-mail: a.hibbert@qub.ac.uk

Received: 9 September 2011
Accepted: 6 October 2011

Abstract

Aims. We report electric quadrupole and magnetic dipole transitions among the levels belonging to 3d⁶4s, 3d⁷ and 3d⁵4s² configurations of Fe II in a large scale configuration interaction (CI) calculation.

Methods. The CIV3 code developed by Hibbert and coworkers is used to determine configuration interaction wave functions for these levels: for the optimisation of two different sets of orbitals based on alternative choices of the 3d function, for creating and diagonalising the Hamiltonian matrices and finally for calculating transition probabilities.

Results. Where possible, we have used experimental energies, not only for transition energies but also to enhance the accuracy of our ab initio CI expansions. We compare our results with those of other authors, and discuss differences between them. The good agreement between our results obtained for the same transitions but with different d-functions indicates that we have treated the state dependence of the d-functions sufficiently well. Most of our results are available in electronic form as an appendix to the paper.

Conclusions. Our analysis of our own results and those of others suggests that many of our transition rates are more accurate than the rather conservative 20−30% we have stated in the text, though in a small proportion of transitions, we could not justify an accuracy greater than this.