Since our RDF-correction is based on an estimation of the excluded volumes in a finite simulation cell, we will now try to isolate the contribution of the excluded volume itself to the total scattering signal. For a solute-solvent system, we can choose to tally up contributions to the scattering arising from the interaction between the two subsystems in the following terms: (1) I uv (q) + I vu (q) = I c (q) from the solute-solvent RDFs (see eq. 2), (2) The part of the solvent-solvent scattering term I vv (q) = I v (q) that encodes the local structure in the shell around the solute, and (3) the part of I v due to the excluded volume 'hole'. While the second and third contributions aren't directly available in isolation from eq. 2, both contributions are encoded in the solvent-solvent RDFs and thus in I v (q). However, the hole, and the subtle changes in average pairwise particle distances within the solvation shell compared to the bulk solvent are averaged out over the bulk-solvent average pairwise particle distances, and are thus extremely sensitive to numerical sampling noise. Furthermore, calculating I v (q) from RDFs sampled in fixed-cell simulations can give rise to an additional finite-size effect, separate from the one discussed in the previous sections. Let us suppose one wishes to analyse a system where the overall extension of the solute changes upon some perturbation to it (for example an electronic excitation), such that the solvation shell expands. For fixed cell (NVT) simulations, such a local expansion will lead to a decrease in effective volume available to the solvent, resulting in a bulk-solvent density increase. The scale of this effect is dependent on the size of the simulation cell, as in a(n equilibrium) simulation of an infinite system, the solvent would have space (and time) to reorganize itself to its preferred density. If preferred, such an effect could be eliminated by re-equilibrating the system after the solvent shell expansion in the NPT ensemble. However, the density fluctuations in such runs will make it difficult to eliminate this effect in a systematic manner. Instead, we will focus on a different route that does not rely on the solvent-solvent RDFs.