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

Effective collision strengths for transitions among the ten energetically lowest fine-structure levels belonging to the (1s22s22p6)3s2, 3s3p and 3p2 configurations of Fe XV have been calculated in the electron temperature range of 105-107 K, using the recent Dirac atomic R-matrix code of Norrington and Grant. The results are compared with the other recently available independent Breit-Pauli R-matrix calculations of Eissner et al (Eissner W, Galavis M E, Mendoza C and Zeippen C J 1999 Astron. Astrophys. Suppl. 137 165) and Griffin et al (Griffin D C, Badnell N R, Pindzola M S and Shaw J A 1999 J. Phys. B: At. Mol. Opt. Phys. 32 2139, 4129). Large differences are observed for many transitions over almost the entire temperature range. These differences are analysed and discussed, and the accuracy of the calculations is assessed. (author). Letter-to-the-editor