The bottom plot in the figure relates the Fe-O distances from the various poses in the MM thermal sampling to the same distances obtained from the B3LYP-D3(BJ) and OPLS/TIP4PEW geometry optimizations (fully drawn lines and dash-dotted lines, respectively). The waterposes within the MM-shells of each frame of the trajectory were determined by aligning each MM frame to the B3LYP-D3(BJ) geometry, and locating each MM-oxygen's closest B3LYP-D3(BJ) counterpart, by searching for the closest B3LYP-D3(BJ) for each of the 17 MM waters. The minimum distance between any oxygens in the B3LYP-D3(BJ) geometry is d min = 2.77 Å. If no B3LYP-D3(BJ) oxygen could be found within d min /2 of the MM water, the MM water pose was determined as "unlabeled", i.e. not able to be unambiguously determined as being in either of the 4 poses. In the gas-phase, the average OPLS/TIP4PEW Fe-O distances are 0.11 Å, 0.15 Å, 0.07 Å, and 0.08 Å longer than for the DFT model, for poses A-D respectively. Thermally averaged at 300 K, all average Fe-O distances increase We can also sample and compare Radial Distribution Functions (RDFs) of solute-solvent spatial correlations. The RDF is the ratio between the (spherically symmetric) local number density of particles, sampled in spherical shells along r from the each i'th particle, to every other j'th particle, δ(|r i -r j | -r), and the bulk density ρ: