Atomic data from the IRON Project

Abstract

As part of the IRON Project, electron impact excitation effective collision strengths are computed for the ion Fe xvi familiar in solar spectra. A Breit–Pauli R-matrix calculation is performed with a 12-level () target representation. The calculation for this relatively simple ion is approached as a test case where we can analyze in detail most of the effects that contribute to the accuracy of the collision strengths: the energy mesh, relativistic corrections, the asymptotic multipole potentials and contributions from high partial waves. By comparing with two recent independent calculations, an accuracy rating of 10% is assigned to the present effective collision strengths in the electron-temperature range of .