We then used an empirical descriptor of the geometric size of the largest conjugated ⇡-system. While better correlated to GFN2/D4 polarizability than HOMO-LUMO gap, this information was not enough to meaningfully correct large polarizabilities (Figure ). Plotting DFT polarizabilities against GFN2/D4 polarizabilities for the PubChemQC subset and the "wide range" set, we examine the e↵ects of using a polynomial fit. As an aside, because the PubChemQC subset and "wide range" sets were computed at di↵erent times using slightly di↵erent methods, with Gaussian with a dispersion correction and with ORCA without a dispersion correction, respectively, the functional has been labeled !b97X(D) here to indicate that for part of the data set a dispersion correction was used. We do not believe the dispersion correction or program makes a meaningful di↵erence in this case, as shown by the low MAE demonstrated for a sample of PubChemQC species in Table , and therefore the PubChemQC and "wide range" results may be grouped together and treated as one large dataset. We note that a quadratic fit provides a better correlation description than a linear fit, where the former has a MAE of 2.47 Å3 compared to !B97X(D), while the latter has an MAE of 7.94 Å3 compared to !bB7X(D) (Figure ). As an aside, for comparison and the sake of completeness, we also tested the correlation between DFT and sTDA-xTB, a simplified time-dependent DFT procedure with a larger inherent basis set. This yielded worse results, with a linear fit MAE of 15.85 Å(Figure ). We therefore conclude that although not as physically meaningful as an adjustment based on a related molecular property, we find a quadratic fit with zero intercept provides the best correction to GFN2/D4 for large polarizability calculations, and note the linear coe cient remains close to unity.