Effective collision strengths for transitions in Fe XI

Collision strengths for transitions among the lowest 48 fine-structure levels belonging to the (1s22s22p6) 3s23p4, 3s3p5, 3s23p33d and 3p6 configurations of Fe XI have been calculated using the Dirac Atomic R-matrix Code (DARC) of Norrington & Grant (2003). Results are tabulated at energies above thresholds in the range Ry, although resonances have been resolved in a fine energy mesh in the thresholds region. Effective collision strengths, obtained after integrating the collision strengths over a Maxwellian distribution of electron velocities, are also tabulated over a wide electron temperature range below K. Comparisons with other available results are made, and the accuracy of the present data is assessed.