While we are aware that because of its minimal basis set approach GFN2 is best geared toward polarizability calculations for small molecules, we believe it is important to test its performance on a range of species, including conjugated oligomers. We are interested in the viability of GFN2/D4 additive polarizabilities for two primary reasons: first, to test them as resource-inexpensive albeit relatively low accuracy calculations that allow for bulk molecular screening. For example, because of its vast speed-up compared to ab initio methods, we previously used GFN2/D4 to calculate the polarizabilities of novel hexamer structures generated by a genetic algorithm (GA)-driven search for high-dielectric organic conjugated oligomers. For that work, we chose to use GFN2/D4 despite suspecting a degree of inaccuracy at high polarizabilities. The speed-up GFN2/D4 provides over DFT methods was necessary to complete the thousands of hexamer polarizability calculations in a reasonable amount of computation time. We qualified our work by noting that while GFN2/D4 appeared to vastly underestimate large polarizabilities, it appeared to do so in a systematic way, such that the order of the polarizabilities' magnitudes relative to one another was preserved (allowing us to accurately rank molecules by polarizability, as was needed for the GA). The second reason we believe it is both relevant and important to test GFN2's ability to calculate polarizabilities for a wide range of chemical species is that shares the additive polarizability model with the D4 disperson-correction method, which is widely used for a variety of species including those not limited to the types of small molecules for which GFN2 has been calibrated.