Atom-wise bond target prediction Some of the bond features are related to each of the atoms. To keep permutation invariance, it was impossible to predict them in the previous step. The task was solved by concatenating embeddings of the atom in question and the corresponding bond and then passing it into the MLP. Polarization values prediction was optimized with MSE loss. Orbital characters were optimized with cross-entropy loss. Similar to the previous section, MSE and the R 2 score were used to control the training.