We now consider the structure of the molecular clusters through modeling. We have taken two approaches to probing structure. One is to use MD simulations of large ensembles of atoms that can sample many different conformations and packing arrangements that might be present in the liquid. The other is to create small molecular clusters directly. These were energy-minimized, as discussed in the Experimental Section, but are not expected to be fully equilibrium structures because the energies are calculated for bare molecular clusters that are not embedded in a background of the liquid. Nonetheless, we can derive interesting insights about the origins of the features in the ddG signals in this way, since for both the MD and small-box ensembles, we can calculate the total PDF (the approach for computing the molecular cluster structure PDFs, GMCSs, is described in the Experimental Section).