, and R T 1 , were extracted, allowing us to compare the dynamics of the PEG molecules from G-CG simulations to the AA simulations. Our results show that the inter-molecular term, R T 1 , from G-CG-H compares well to AA (Fig. ). Our results also show that in the low PEG concentration limit, c PEG → 0, there is no visible difference in R T 1 between G-CG-H / AA and G-CG trajectories. This is expected as inter-molecular distances are typically much larger than intra-molecular distances in the diluted limits, and therefore the typical distances between CoM and atoms from different molecules are similar. Comparison between AA and G-CG-H trajectories for R R-bead 1 and R R-chain 1 also show good agreement (Fig. ). It should be noted that the excellent prediction of R 1 by G-CG-H does not imply that G-CG-H trajectories reproduce perfectly the molecular dynamics, or that G-CG and AA systems share the same properties. For instance, the viscosity of the G-CG simulations, as calculated using the same protocol as for the AA simulations, is systematically larger than the experimental viscosity, by a factor up to 3 for the largest values of c PEG (Fig. ). Such discrepancies in viscosity between AA and G-CG models are well documented , and are typically attributed to the missing degrees of freedom in the G-CG models, and to differences between the use of an explicit (AA) and implicit (G-CG) solvents. In addition, the molecular motion of the PEG molecules, as predicted by the G-CG-H trajectory, differs from the AA simulation, as evidenced by comparing the correlation functions (Figs. S8) and the full R 1 spectrum (Figs. S9).