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DY: Fachverband Dynamik und Statistische Physik

DY 36: Condensed-matter simulations augmented by advanced statistical methodologies (joint session DY/CPP)

DY 36.8: Talk

Wednesday, April 3, 2019, 17:15–17:30, H20

Understanding three-body contributions to coarse-grained force fields — •Christoph Scherer, Rene Scheid, Tristan Bereau, and Denis Andrienko — Max-Planck-Institut für Polymerforschung, Mainz, Germany

Coarse-graining (CG) is a systematic reduction of the number of degrees of freedom (DOF) used to describe a system of interest. CG can be thought of as a projection on the CG DOF and is therefore dependent on the number and type of CG basis functions. We present an extension of the two-body basis set with three-body basis functions [1]. The CG scheme is implemented in the VOTCA-CSG toolkit [2]. We show that naive extensions of the CG force field can result in substantial changes of the two-body interactions making them much more attractive. This is related to the three-body basis functions of the Stillinger-Weber type having a significant two-body component. This interference can be alleviated by CG the two-and three-body contributions separately. Furthermore, we employ Kernel-based Machine learning (ML) [3] overcoming the restrictions of a fixed basis set. The approach is illustrated on liquid water where three-body interactions are essential to reproduce the structural properties, and liquid methanol where two-body interactions are sufficient to reproduce the main features of the atomistic system. [1] Scherer, Andrienko, PCCP, 20, 22387 (2018); [2] Rühle, Junghans, Lukyanov, Kremer, Andrienko, JCTC, 5, 3211 (2009); [3] Glielmo, Sollich, De Vita, PRB, 95, 214302 (2017)