Nature of interacting resonances in electron-ion excitation

The calculations of Badnell et al. [Phys. Rev. A 48, R2519 (1993)] demonstrated an apparent breakdown on the isolated-resonance approximation within certain resonant contributions to the 3s² ¹S{→}3s3p ³P transition in Fe¹⁴⁺. We have now carried out detailed analyses of selected resonant structures for this transition. Comparing calculations using the independent-processes and isolated-resonance approximation, interacting resonance theory, and the R-matrix close-coupling method, we determine the nature of the interactions between resonances and demonstrate the sensitivity of the size of the resonant contribution to the positions of the resonances.