Prior to including explicit solvent, we first consider a model trained on DNA only data (Table ) to assess the strategy of fragmenting the DNA base-pair step. We compare density prediction errors ϵ ρ M L and ϵ ρtrue (see Computational Methods) from the current fragment-trained model and the previous model trained on the entire DNA base-pair step . Note that the accuracy of the previous model has been improved from what was reported by normalizing the coefficients to electron populations (see S1