Reverse CG (RCG) methods allow to reconstruct atomistic details from their corresponding CG representation . RCG was performed using a numerical procedure similar to the one developed by Rzepiela et al. , here implemented using LAMMPS . First, an AA simulation containing a single PEG molecule was performed. Harmonic potentials between the CoM of each monomer and the positions of the beads extracted from the G-CG simulation were added. Then, the energy of the system was minimized using steepest descent. This minimization step was conducted for every frame until a full trajectory was obtained for each PEG molecule, and then all the molecules were merged and wrapped into a single simulation trajectory. The final trajectory, called G-CG-H where the '-H' refers to the reconstructed hydrogen atoms, was then used for calculting NMR relaxation rate R 1 using Eqs. .