For MD simulations, the local density is simply numerically histogrammed using finite-sized r-bins, and averaged over many frames. Thus, one can choose e.g. to sample the Fe-O RDF Figure : Distribution Functions (RDFs) of the Fe-water oxygen correlation in the liquid phase. Top: The dotted line shows the results from the MM OPLS/TIP4PEW simulation used in the connection to the vacuum-relaxed geometries from figure . The MM RDFs, here sampled in NPT, are in agreement with the NVT-sampled MM RDFs in a previous study. The fully drawn and dashed lines have been digitized from the work by L. M. L. Daku and L. M. L. Daku & A. Hauser, respectively, simulating fully QM systems using BLYP, with and without the D3 long-range dispersion correction. Bottom: Comparisons of the solvation shell changes from LS-HS excitation. The BLYP-D3 results show a decrease in amplitude of the first peak, and both the first and second solvent shell average distance increases. For the OPLS/TIP4PEW results, the changes are less pronounced. by letting i only run over the (single) Fe atom in the simulation, and j over all water-oxygens in the box. The black dotted line in figure shows the Fe-O water radial distribution function (RDF) sampled from the OPLS/TIP4PEW dynamics simulation, compared to the two AIMD simulations from literature. A previous study performed a similar comparison, focusing on the effect on which partial charge-generation method is used. As none of the charge-generation methods could fully reproduce the dispersion-corrected AIMD RDF, we have limited ourselves to only using the CHELPG-charge generation method here, focusing instead on comparing the differences in the liquid structure to the differences found in the interaction curves of the previous section, to analyse the seemingly nonelectrostatic origin of the differences in the liquid-phase descriptions. The MM RDF resembles the non-dispersioncorrected AIMD RDF most closely, with almost equivalent peak distances. The thermally averaged BLYP-D3 solvent shell is more structured, with shorter characteristic Fe-O distances, indicating that the long-range dispersion effect on solvation shown to be important in the previous sections are not captured completely by the MM model. Comparing to figure , we observe that all the identified characteristic poses lie within the first RDF peak, as expected. We note that the second RDF peak, signifying the second solvation shell centered around Fe is thus only indirectly affected by Fe-water interactions. The large LS-HS changes in solvation structure predicted by the AIMD simulations are less pronounced in the MM model.