Inner-shell photoabsorption ofFe14+:Unimportance of correlation and relativistic effects

We have performed a series of calculations of the photoabsorption cross section of ${\mathrm{Fe}}^{14+}$ near the ${2p}^{-1}$ and ${2s}^{-1}$ edges, within the framework of R-matrix theory. We find the unexpected result that the inclusion in the calculation of such effects as the spin-orbit interaction and higher-order correlations leads to a mere redistribution of flux among the various final channels, while the total convoluted photoabsorption cross section remains virtually unchanged. Hence, an appropriate minimal configuration $\mathrm{LS}$ coupling representation can adequately describe inner-shell total photoabsorption cross sections, leading to a saving in computational effort by orders of magnitude compared to more elaborate calculations.