Apart from the obvious differences in level of sophistication between ab initio models and classical potentials, other simulation parameters can play a role on the final solvation structure. The AIMD simulations include explicit treatment of the electronic density of the entire system in their model, which of course comes at much higher computational cost. This limits the size of the simulation boxes that can reasonably be computed. The bulk density used to produce the RDF in equation 2 for periodic-but finite systems (i.e. sampled in NVE, NVT, or NPT) is calculated as the number of particles over the simulation box volume.