Collision strengths for transitions among the 3s2, 3s3p and 3p2 configurations of Fe XV

Collision strengths for transitions among the energetically lowest 10 fine-structure levels belonging to the (1s22s22p6) 3s2, 3s3p and 3p2 configurations of Fe XV have been computed at energies below 160 Ryd, using the recent Dirac atomic R-matrix code (DARC) of Norrington and Grant. The results are compared with the two recently available independent Breit-Pauli R-matrix calculations of Griffin et al (1999 J. Phys. B: At. Mol. Opt. Phys. 32 2139) and Eissner et al (1999 Astron. Astrophys. Suppl. 137 165). Large differences are observed, especially with the former calculations. Effective collision strengths have also been compared between their results, and it is concluded that the values reported by Griffin et al are inaccurate for many transitions. (author). Letter-to-the-editor