For this section, non-relaxed dissociation curves for the first excited state of the benzene dimer were generated with CC2 and SCS-CC2 and various AO basis sets. While CC2 and SCS-CC2 both yield reliable excitation energies, albeit still above the related chemical-accuracy threshold of 0.1 eV, benchmark studies suggest that the latter does not show consistent improvement to vertical excitation energies in general. However, enhanced excited-state geometries and vibrational frequencies could lead to more accurate 0-0 transition energies for π → π * and n → π * excitations. Therefore, any potential improvements for SCS-CC2 seem to be problem specific, hence we need to carry out a comparison with CC2.