Due to our interest in finding an e cient method for calculating molecular polarizabilities for novel molecular searches, we sought to test the accuracy of GFN2/D4 on common small molecules. As an initial experiment, we calculated the polarizabilities for approximately 8,400 species from the PubChemQC dataset, using both GFN2/D4 and DFT with the !B97XD functional 36 and the cc-pVTZ basis set. Although this does not allow polarizabilites to be as accurate as when calculated with augmented basis sets, it allowed us to perform thousands of calculations quickly and gave us an initial baseline against which we could compare GFN2/D4. As discussed below, such results can be scaled to augmented basis sets.