To support this point, the dashed curve in Fig. (a) was generated using eqn (2) with the same parameters as the solid curve, except for 𝜁 , which was increased from 1.05 (solid curve) to 1.30 We note that the differences between the EOM-EA/SF and EOM-IP approaches are ultimately rooted in approximate treatment of electron correlation. These differences are expected to decrease and eventually disappear when higher excitations are included (triples, quadruples, ...), as the two treatments become equivalent at the full configuration interaction limit.