Atom, lone pair, and bond nodes The most straightforward problem to solve is the prediction of targets for individual nodes. Here, for all types of nodes, only one network is used. The loss function was defined as a sum of separate losses for each node type. For all features except orbital characters of lone pairs, the mean squared error (MSE) loss was used. Orbital character prediction was optimized with a cross-entropy loss function. MSE was also the key metric for this type of task. R 2 scores were also recorded.