A shortcoming of atomic additive methods is that the same polarizability is predicted for all structural isomers, since only the total number of each atom-types is used in the prediction. This is manifested in Fig. as having a systematic error within each possible α pred value, and further demonstrated in the inset on the case of molecules with chemical formula C 6 H 8 O. Indeed, the reference polarizabilities for this given chemical formula span a range of 30 a.u., but the predicted value is 73.4 a.u. for all molecules, irrespective of the chemical arrangement of the atoms. From Fig. , it can also be inferred that such a simple additive model will only become worse for molecules of increasing size. Indeed, a trend appears where larger molecules exhibit stronger deviations towards higher polarizabilities -a trend that an additive model is unable to describe. This can be especially the case for polymeric molecules which form long chains, whose polarizability is highly anisotropic and it behaves increasingly non-additively with size.