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

Abstract

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.

Extended coarse-grained dipole model for polar liquids: Application to bulk and confined water

“…Sanyal and Shell [42] have developed a local density-based approach that modifies the fluid-fluid interactions through a local density potential function. Wagner et al [43] proposed an order-parameter dependent potentials, in which they have used the multiscale coarse-graining (MS-CG) approach [44,45] where the order parameter can be local, such as local density at a CG site, or global, such as the distance from a wall. In this study, we use the approach of Mashayak et al [41], except that we use the bulk-based CG pair potential for the fluid-fluid interaction and optimize the wall-fluid interaction within the RE framework.…”

Assessing the transferability of common top-down and bottom-up coarse-grained molecular models for molecular mixtures

“…This includes interactions which are transferable between bulk liquids and liquid-liquid interfaces, which is a notable improvement in chemical transferability. 39,65,[111][112][113]…”

“…The comparisons made between atomistic and coarse-grained models are all based on calculations using the standard atomistic expressions for the relevant observables; however, we do note that in some cases these comparisons may not be strictly valid when the coarse-grained model is state-point dependent. 39…”

Dynamics of Co-translational Membrane Protein Integration and Translocation via the Sec Translocon

“…51 Despite the aggressive simplifications employed, extensive benchmarking with respect to experimental 10 results 5,13,16,19,[52][53][54] -which is summarized in the following sections -reveals that the CGMD model provides a reasonable description of co-translational integration and secretion. We emphasize that other coarse-graining strategies [55][56][57] could be employed to further refine the CGMD model.…”