has been suggested to quantify the density sensitivity of a given functional Ẽ[ρ], by comparing the energy evaluated using self-consistent densities obtained either from a HF calculation (ρ HF ) or else a local density approximation (LDA, ρ LDA ). For small molecules, values S > 2 kcal/mol are suggested as cases where DC-DFT may improve the results. For the cluster models in Fig. , values of S computed using the PBE and BLYP functional are provided in Table . Values S > 30 kcal/mol for Al(OH) 4 and S > 120 kcal/mol for the largest cluster indicate that the density sensitivity is indeed high.