Berlin 2018 – wissenschaftliches Programm

Bereiche | Tage | Auswahl | Suche | Aktualisierungen | Downloads | Hilfe

CPP: Fachverband Chemische Physik und Polymerphysik

CPP 63: Polymer and Molecular Dynamics II

CPP 63.11: Vortrag

Donnerstag, 15. März 2018, 12:15–12:30, C 264

Towards understanding three-body contributions to coarse-grained force fields — •Christoph Scherer and Denis Andrienko — MPIP, Mainz, Germany

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 of the Stillinger-Weber type with a flexible angular potential. The CG scheme is implemented in the VOTCA-CSG toolkit [1]. 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 having a significant two-body component which we examine in detail by decomposing the two-body potential of mean force (PMF). This interference can be alleviated by CG the two- and three-body forces separately which also helps to evaluate the importance of many-body interactions for a given system. The approach is illustrated on liquid water where three-body interactions are essential to reproduce the structural properties [2,3], and liquid methanol where two-body interactions are sufficient to reproduce the main features of the atomistic system. Our findings motivate to systematically extend the CG basis set in a way to clearly separate the many-body contributions of different order. [1] Rühle, Junghans, Lukyanov, Kremer, Andrienko, JCTC, 5, 3211 (2009); [2] Molinero, Moore, JPCB, 113, 4008 (2009); [3] Larini, Lu, Voth, JCP, 132, 164107 (2010)