Electron-impact excitation cross sections for Fe 16 + in the configuration-average distorted-wave approximation

Electron-impact excitation cross sections for the $2{p}^{6}\ensuremath{\rightarrow}2{p}^{5}3l$ transitions in ${\mathrm{Fe}}^{16+}$ are calculated in a configuration-average distorted-wave approximation. Resonant-excitation contributions from the $2{p}^{5}3pn{l}^{\ensuremath{'}}$, $2{p}^{5}3dn{l}^{\ensuremath{'}}$, and $2{p}^{5}4ln{l}^{\ensuremath{'}}$ series are included in the isolated resonance approximation. The accuracy of the distorted-wave calculations is determined by comparison with previous 139 level resolved $(n\ensuremath{\leqslant}5)$ fully relativistic $R$-matrix calculations. Excellent agreement is found between the configuration-average distorted-wave and $R$-matrix total rate coefficients for the strong $2{p}^{6}\ensuremath{\rightarrow}2{p}^{5}3p$ and $2{p}^{6}\ensuremath{\rightarrow}2{p}^{5}3d$ transitions, while differences found for the relatively weak $2{p}^{6}\ensuremath{\rightarrow}2{p}^{5}3s$ transition are mainly attributed to close-coupling effects.