m Real systems, like a molecule in solution, will most often be comprised of many different elements. This section will use the transition metal complex [Fe(bpy) 3 ] 2+ as an example, as it has been the center for many experimental studies using x-ray techniques , including scattering , as well as computational investigations . The complex is shown in the lower right corner of fig. . From the geometry of the complex, it is evident that the simple spherical approximation of the excluded volume will be much less accurate than previously. The complex is comprised of a single Fe atom, plus atoms of the elements C, N, and H, and according to eq. 3 the coherent cross term scattering signal I c (q) is a stoichiometrically weighed sum of the integrals over the cross-term RDFs, each term multiplied with the atomic form factors of the atom types of the RDF. It is thus clear that each pairwise correlation does not contribute equally to the recorded signal, but that its intensity is dependent on the number of atoms of each type present in the system, as well as the number of electrons in each atom type. But I c (0; R) will show the same behaviour as S c (0; R), as the form of the integral is the same. Therefore, to make a single assessment of the convergences of all the integrals that are evaluated to obtain I c (q), taking into account how much each term contributes to the total cross-term signal, we use I c (0; R) instead of all the individual S c (0; R) terms. The top three plots in fig. shows the results of applying each of the three corrections to each of the cross-term RDFs. For the volume-correction, the excluded volume was fitted separately for each RDF. For this relatively large molecule, the first thing we observe is how the two first corrections struggle to make the running integral reach convergence within the limited box size. However, close inspection of the results from the van der Vegt correction shows that the curves seem to flatten out above ∼27 Å, indicating that convergence might be reached for this correction. We repeated the strategy of performing the simulations at increasing densities in order to study the robustness of the fitted excluded volume from the long-r RDF asymptote. The middle plot shows the result of these fits. We first note that the excluded-volume values are larger than expected for a single atom of the same type in a solution. This is because the rest of the particles in the solute will hinder access of the solvent molecules. Yet, in spite of the now somewhat crude spherical approximation of the excluded volume, we still observe the expected behaviour of the volume decreasing with increased density, no matter which of the solute-solvent RDFs we fit. While all pairs produce excluded volumes of similar sizes for each water density, the intercalation of water molecules between the ligands of the complex (see the inset in fig. ) means that the waters of the first solvation shell can get closer to especially the carbon atoms of the complex. This effect causes the smaller fitted excluded volume values from those correlations.