On the computations of decay widths of Fano resonances

In this paper we present an ab initio approach to the computation of decay widths of Fano resonances. The method relies on Fano theory, in which a resonance is described as a bound state embedded in and interacting with a continuum of states. In our approach, we use the Configuration Interaction (CI) method to describe the bound-like and continuum-like parts of the resonance wave function. The aim of this Fano-CI method is to provide decay widths of resonances at a low computational cost such that large systems can be treated. Along with the implementation of the method, we present benchmark calculations of decay widths of Auger and ICD processes in Ne atom, and Ne₂ and NeAr dimers. Our results are in good agreement with the decay widths from other theoretical and experimental works. This makes the Fano-CI approach a promising method for the treatment of Fano resonances.