As shown in the above assessment, GFN2/D4 performs well when calculating relatively small isotropic polarizabilities, in the range <50 Å3 common for most small molecules. For species with larger polarizabilities, especially for long conjugated systems like the hexamers in the "wide range" set, GFN2/D4 appears to systematically underestimate the polarizability. This derives from its use of an atom-additive polarizability model, neglecting the nonlocal polarizability-enhancing e↵ects of electron delocalization. Our results suggest a correction is needed to allow GFN2/D4 to more accurately predict larger polarizabilities.