Investigation of Coarse-Grained Mappings via an Iterative Generalized Yvon-Born-Green Method

The interactions in CG models are often iteratively refined over multiple simulations until they reproduce the one-dimensional (1-D) distribution functions, e.g., radial distribution functions (rdfs), of an all-atom (AA) model. In contrast, the multiscale coarse-graining (MS-CG) method employs a generalized Yvon-Born-Green (g-YBG) relation to determine CG potentials directly (i.e., without iteration) from the correlations observed for the AA model. However, MS-CG models do not necessarily reproduce the 1-D distribution functions of the AA model. Consequently, recent studies have incorporated the g-YBG equation into iterative methods for more accurately reproducing AA rdfs. In this work, we consider a theoretical framework for an iterative g-YBG method. We numerically demonstrate that the method robustly determines accurate models for both hexane and also for a more complex molecule, 3-hexylthiophene. Additionally, we demonstrate a simple and predictive analysis for determining CG mappings that promote an accurate description of intramolecular states (molecular conformations) sampled by the atomsitic model.