Dynamically consistent coarse-grained models of chemically specific polymer melts via friction parameterization*

Coarse-grained (CG) models of polymers are developed to reduce computational effort yet capture the relaxation behavior imparted by the hierarchal structure. Bottom-up CG methods are parameterized using atomistic reference data, and in the case of Iterative Boltzmann inversion (IBI), target the recovery of the chemically specific structure and thus thermodynamics, but at the cost of dramatically sped up dynamics. Here, we aim to develop a chemically specific, thermodynamically consistent, and dynamically correct model by combining a conservative potential and a dissipative potential. The conservative potential is parametrized via IBI from short atomistic simulations; the CG force-field is tuned to recover the pair distribution function of the atomistic representation, and thus, thermodynamics. The dissipative potential is introduced to correct the dynamics of the CG force-field. Here, we apply a Langevin thermostat and characterize the friction factor needed to recover atomistic dynamics. We discuss the consistency of the parameterizable friction factor for melt state oligomers as characterized by multiple modes of dynamics and property calculations.