With this insight, we now turn to the MD simulations. Details of the calculations are described in the Experimental Section. After equilibrating the ensembles (a representation is shown in Figure ), we calculate total PDFs of the modeled amine-water mixtures. We also equilibrate MD ensembles of pure water and pure DIPA at the same temperatures and pressures, calculate their total PDFs, G(r), and use the modeled pure-component PDFs to extract an MD-derived double differential PDF, ddG(r), according to the same method as the experimental PDFs. As shown by the blue lines in Figure and, both the MDderived Gs and ddGs are in excellent agreement with the experimental results. The remarkable agreement of the ddGs suggests that the MD simulations reproduced accurate molecular arrangements at the level of the precision of the experimental PDF measurements, giving confidence that we can learn about molecular arrangements from the MD ensembles.