Electron-impact excitation of the iron peak element Fe V

We describe a successful implementation of a version of the R-matrix method reformulated with physical and numerical parallelization in mind, and apply it, as a prototype example, to the calculation of optically forbidden electron-impact excitations of Fe⁴⁺ as a function of energy. Total collision strengths are derived for Maxwellian electron energy distributions in the temperature range 5 × 10³–10⁶ K using a new parallel program PRMAT. Previous attempts to calculate collision strengths for open d-shell ions of this type using scalar programs have been prohibitively lengthy because of the need to take account of the very large number of target states and coupled scattering channels which arise. The present results were obtained in LS-coupling using 80 target states and up to 228 scattering channels.