Extending the range and physical accuracy of coarse-grained models: Order parameter dependent interactions

Order parameters (i.e., collective variables) are often used to describe the behavior of systems as they capture different features of the free energy surface. Yet, most coarse-grained (CG) models only employ two- or three-body non-bonded interactions between the CG particles. In situations where th...

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Bibliographic Details
Published in:The Journal of chemical physics 2017-07, Vol.147 (4), p.044113-044113
Main Authors: Wagner, Jacob W., Dannenhoffer-Lafage, Thomas, Jin, Jaehyeok, Voth, Gregory A.
Format: Article
Language:English
Subjects:
Acetonitrile
Free energy
Granulation
Mathematical models
Model accuracy
Multiscale analysis
Order parameters
Phase transitions
Physics
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Summary:Order parameters (i.e., collective variables) are often used to describe the behavior of systems as they capture different features of the free energy surface. Yet, most coarse-grained (CG) models only employ two- or three-body non-bonded interactions between the CG particles. In situations where these interactions are insufficient for the CG model to reproduce the structural distributions of the underlying fine-grained (FG) model, additional interactions must be included. In this paper, we introduce an approach to expand the basis sets available in the multiscale coarse-graining (MS-CG) methodology by including order parameters. Then, we investigate the ability of an additive local order parameter (e.g., density) and an additive global order parameter (i.e., distance from a hard wall) to improve the description of CG models in interfacial systems. Specifically, we study methanol liquid-vapor coexistence, acetonitrile liquid-vapor coexistence, and acetonitrile liquid confined by hard-wall plates, all using single site CG models. We find that the use of order parameters dramatically improves the reproduction of structural properties of interfacial CG systems relative to the FG reference as compared with pairwise CG interactions alone.
ISSN:0021-9606
1089-7690
DOI:10.1063/1.4995946