Electron-impact excitation of the iron peak element Fe V

Abstract

We describe a successful implementation of a version of theR-matrixmethod reformulated with physical and numerical parallelization in mind, andapply it, as a prototype example, to the calculation of optically forbiddenelectron-impact excitations of Fe4+ as a function of energy. Total collisionstrengths are derived for Maxwellian electron energy distributions in thetemperature range 5 × 103–106 K using a new parallel program PRMAT. Previousattempts to calculate collision strengths for open d-shell ions of this typeusing scalar programs have been prohibitively lengthy because of the needto take account of the very large number of target states and coupledscattering channels which arise. The present results were obtained inLS-couplingusing 80 target states and up to 228 scattering channels.