There are three possible explanations for the high performance of our model. First, the size of our training set is 100 times larger than that of the previous study. It may decrease the risk of overfitting to a small set of molecules. Second, non-Coulomb interactions that were not considered by an atom-pair Coulomb interaction matrices may carry important information. The ECFP, MACCS keys, and molecular descriptors are able to capture local environments including the effects of non-Coulomb interactions. Third, the depth of layers in their model was four, which may be too shallow to learn the electronic properties accurately.