The loss function is minimized using the AdamW 56,57 optimizer, with default parameters, and a per-layer weight-decay analogous to the one used in the training procedure for the ANI-2x model. The network architecture and descriptor parameters are the same as those used in ANI-2x. The output value output from the final layer of the network, which we will call q * i , is not used directly in the loss function; it is instead normalized by multiplying it with a factor f i (q * m ) that depends on all values output by the atomic networks for a given molecule, and guarantees that the sum of the atomic charges is equal to the charge of the QM region (neutral in all the results we present in this article). We found a normalizing factor given by: