The ∆SCF approach has been benchmarked and thoroughly studied for both molecules and solids, yet is not without problems. For one, the core hole represents an unstable (saddle-point) solution to the SCF equations and there is no guarantee that such a solution can be located, although in our experience this is a larger problem for core excitation than it is for core ionization, meaning that the problem lies with the particle in the virtual space rather than the hole in the occupied space. Sensitivity with respect to the choice of exchange-correlation (XC) functional is an altogether different issue. Recent studies have recommend the semilocal SCAN functional for both XPS and xray absorption spectroscopy (XAS). The latter technique is not considered here, but for XPS of medium-size molecules, ∆SCF results based on the SCAN functional exhibit mean absolute errors (MAEs) of ∼ 0.2 eV with respect to experiment. This represents the state-of-theart in DFT-based ∆SCF calculation of CEBEs.