Since the electronic energies given by DFT codes are large, and those reported for tmQM are nonnormal, additional preprocessing was employed to get the targets close to zero and normally distributed. A reference correction strategy was used, wherein the average energy attributable to each element was computed via a linear regression over the dataset and then subtracted from the total energy, which yields a surrogate of the formation energy of the structure. The original distributions of energies, as well as the distributions after reference correction, are shown in the SI (under 'Energy Distributions'). The energies attributed to each element through this strategy are also reported in the SI (under 'Atomic Energies Used for Reference Correction'), for both the entire tmQM dataset and the neutral subset. Finally, the data was split between training, testing, and validation sets, using an 80/10/10 split for both all of tmQM and the neutral subset. These splits are included in the supporting code.