Systematic Coarse-Graining of Microscale Polymer Models as Effective Elastic Chains

One of the key goals of macromolecular modeling is to elucidate how macroscale physical properties arise from the microscale behavior of the polymer constituents. For many biological and industrial applications, a direct simulation approach is impractical due to to the wide range of length scales that must be spanned by the model, necessitating physically sound and practically relevant procedures for coarse-graining polymer systems. We present a highly general systematic coarse-graining procedure that maps any detailed polymer model onto effective elastic-chain models at intermediate and large length scales. Our approach defines a continuous flow of coarse-grained models starting from the detailed microscale model, proceeding through an intermediate-scale stretchable, shearable wormlike chain, and finally resolving to a Gaussian chain at the longest lengths. We demonstrate the utility of this procedure by coarse-graining a wormlike chain with periodic rigid kinks, a model relevant for studying DNA−protein arrays and genome packing. The methodology described in this work provides a physically sound foundation for coarse-grained simulation of polymer systems, as well as analytical expressions for chain statistics at intermediate and long length scales.