IRON Project. LXII. Fe XVIII transitions

All fine structure levels have been identified spectroscopically. Erratum: A bug was detected and corrected in early 2007 in one of the stages called RECUPD (Storey, Berrington, Werner, 2007, private Iron Project communications) of the Breit-Pauli R-matrix (BPRM) codes of the Iron Project. It was related to the the phase factor of dipole matrix elements of the Iron Project (Berrington et al., 1995, Comput.

Phys. Commun. 92, 290) and affected certain transition probabilities. The new results on energies and transition probabilities for Fe XX (Nahar, 2004, J/A+A/413/779) and Fe XVIII (Nahar, 2006, J/A+A/457/721, this paper) using the corrected code are replacing the earlier results at CDS.

It should be noted that stage RECUPD in BPRM codes does not exist in the LS coupling R-matrix code from the Opacity Project (Berrington et al., 1987, J. Phys. B 20, 6379) and hence does not affect the non-relativistic results. Results for other ions, obtained using BPRM codes, did not indicate the bug effect when compared with existing results.

However, I am repeating the calculations for these ions and will replace the earlier results. The E1 transition probabilities for Fe XX have been recomputed. The new files are: table3a, table3b -> fine structure energy levels of Fe XVIII table4a, table4b -> complete table of E1 fine structure transitions in Fe XVIII table5 -> table of fine structure transitions in Fe XVIII using observed energies In paper LIV (Fe XX), J/A+A/413/779, files were also corrected.