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Paper XLII

Electron impact excitation of Fe XXI
K. Butler and C.J. Zeippen
Astronomy & Astrophysics Supplement Series, 2000, Vol.143, pp.483-489

Collision strengths and collisional rate parameters are provided for transitions among the $n=2$ and 2p$3\ell$ levels of C-like Fe XXI. The data have been computed in a 52-state Breit-Pauli approximation thus accounting for the most prominent relativistic effects. An R-matrix close-coupling calculation comprising partial wave contributions up to $J=59/2$ and of order 8000 energy points in the range up to 260 Ryd gave cross sections expected to be accurate to better than 20% for transitions among the $n=2$ levels.