(743e) A Coarse-Grained Model for the Crystalline Structure of I-Alpha and I-Beta Cellulose Based On Force Matching

Cellulosic ethanol production is a two-stage process which involves the hydrolysis of cellulose to form simple sugars and the fermentation of these sugars to ethanol.  Hydrolysis of cellulose is the rate-limiting step and there is a great need to characterize the process with numerical simulation to better understand the complex mechanisms involved.  Our ultimate goal is to generate accurate coarse-grained molecular models of that are capable of predicting the structure of lignocellulose before and after pretreatment so that subsequent ab initio calculations can be performed to probe the degradation pathways. Here, we use the force matching method to derive coarse-grained molecular models capable of predicting the crystalline structures of I-alpha cellulose and I-beta cellulose.  We examine these structures in vacuum and in aqueous solution.  Several coarse-graining mapping strategies are systematically evaluated for the same reference all-atom molecular dynamics simulation trajectories to determine the coarse-grained model that most accurately recovers the reference all-atom structure. Radial distribution functions of coarse-grained sites and the root mean square displacement of cellulose chains are used to validate the coarse-grained model.   Very good agreement is observed between the reference all-atom structures and the corresponding coarse-grained models