Fitting coarse-grained distribution functions through an iterative force-matching method.

An iterative coarse-graining method is developed for systematically converting an atomistic force field to a model at lower resolution that is able to accurately reproduce the distribution functions defined in the coarse-grained potential. The method starts from the multiscale coarse-graining (MS-CG) approach, and it iteratively refines the distribution functions using repeated applications of the MS-CG algorithm. It is justified on the basis of the force matching normal equation, which can be considered a discrete form of the Yvon-Born-Green equation in liquid state theory. Numerical results for molecular systems involving pairwise nonbonded and three-body bonded interactions are obtained, and comparison with other approaches in literature is provided.