Importance of the completeness of the configuration interaction and close coupling expansions in R-matrix calculations for highly-charged ions: electron-impact excitation of Fe ${}^{20+}$

L Fernandez-Menchero, A S Giunta, G Del Zanna +1

We have carried-out two intermediate coupling frame transformation (ICFT) R-matrix calculations for the electron-impact excitation of C-like Fe ${}^{20+}$, both of which use the same…