The DFTB data set consists of 95k molecules with HOMO-LUMO gap generated using the method in Section 3. Ninety percent of the data set is used for model training and the other 10% is split equally for model validation and testing. The AdamW optimizer is used with the learning rate of 10 -3 and the batch size of 64. The model is trained for 200 epochs and the final test MAE for HOMO-LUMO gap is 0.12 eV.