Coarse-grained simulation methods

This chapter will review the generation of free-standing thin films and fibers with a coarse-grained simulation method on a high coordination lattice,performed in a manner that allows accurate reverse-mapping of individual replicas to a fully atomistic representation in continuous space.4 After describing some of the properties of these films and fibers, we will present some new information about the limits on the stability of the models of these nanofibers. 

In Equation 7.2, pt +i represents the probability of the system changing from current configuration i to a new configuration i + 1, AE the change in potential energy associated with the attempted move, the Boltzmann constant, and T the temperature of the system. MC simulations are often performed in NVT and pVT ensembles, and widely applied to polymers as well as polymers in contact with filler particles. Brownian dynamics (BD) and dissipative particle dynamics (DPD) are further particle-based coarse-grained simulation methods similar to MD simulation. BD employs a continuum solvent model rather than explicit solvent molecules in MD and the total force is ... 

Some coarse-grained simulation methods have been estabHshed to understand the structure—property relationships of material interfaces, which include BD, dissipative particle dynamics (DPD), and CGMD based on MARTINI force field, and many efforts have focused on the protein adsorption, interfacial behavior and surface wettabihty, and so on. 

Mesoscale simulation methods [34] bridge between the short length and time scales typically probed by atomistic and coarse-grained simulations at a higher computational cost and the larger scales typically probed by continuum simulations of bulk material behavior. Figure 7.4 is a schematic illustration of length and time scales, adapted from Shelley and Shelley [35]. 

Elezgaray, and Laguerre, M. (2006]. A systematic method to derive force fields for coarse-grained simulations of phospholipids, Computer Physics Communications 175,4, pp. 264-268, doi http //dx.doi.org/10. 1016/j.cpc.2006.01.009, URL http //www.sciencedirect.com/science/ article/pii/S0010465506001585. 

Detcheverry FA, Pike DQ, Nagpal U, Nealey PF, de Pablo JJ. Theoretically informed coarse grain simulations of block copolymer melts method and applications. Soft Matter 2009 5 4858. 

The new method can also be combined with recently proposed coarse-graining simulation strategies for long polymer melts to enable the simulation of the viscoelastic properties of high molecular weight polymers, comparable to those encountered in practical polymer processing. 

A fiirther theme is the development of teclmiques to bridge the length and time scales between truly molecular-scale simulations and more coarse-grained descriptions. Typical examples are dissipative particle dynamics [226] and the lattice-Boltzmaim method [227]. Part of the motivation for this is the recognition that... 

The dynamic mean-field density functional method is similar to DPD in practice, but not in its mathematical formulation. This method is built around the density functional theory of coarse-grained systems. The actual simulation is a... 

It is the interplay of universal and material-specific properties which causes the interesting macroscopic behavior of macromolecular materials. This introduction will not consider scales beyond the universal or scaling regime, such as finite element methods. First we will give a short discussion on which method can be used under which circumstances. Then a short account on microscopic methods will follow. The fourth section will contain some typical coarse-grained or mesoscopic simulations, followed by some short general conclusions. 

The bond fluctuation model (BFM) [51] has proved to be a very efficient computational method for Monte Carlo simulations of linear polymers during the last decade. This is a coarse-grained model of polymer chains, in which an effective monomer consists of an elementary cube whose eight sites on a hypothetical cubic lattice are blocked for further occupation (see... 

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