Coarse grained methods/models

Particle-based methods have been linked to continuum models in order to exploit the efficiency of hnite element schemes and yet account for boundary layers and other regions where continuum approaches may fail [135]. It is very likely that coarse grained methods will continue to be developed and used since many physical systems are too large or too complex to be treated by full MD. 

Between the appearance of the MD studies by Vishnyakov and Neimark [56], and that by Urata et al. [60], Khalatur, Khokhlov and co-workers published two coarse-grained molecular modelling studies of Nafion [64, 65] that utilised rather different approaches to studying the morphology of PFSIs. The first of these [64] was based on a hybrid Monte Carlo/reference interaction site model (MC/RISM). The principle behind this method was to use MC simulations, based on the rotational isomeric state (RIS)... 

Fig. 1.11 (a) A typical coarse-graining method replaces groups of atoms by ellipsoidal rigid bodies, (b) The Gay-Beme potential models the anisotropic interaction between nonspherical coarse-grained molecules potentials are described by the orientation of the molecules with respect to a fixed frame and the separation between their centers of mass... 

Noid WG, Chu JW, Ayton GS, Krishna V, Izvekov S, Voth GA, Das A, Andersen HC (2008) The multiscale coarse-graining method. I. A rigorous bridge between atomistic and coarsegrained models. J Chem Phys 128(24) 244114... 

The parameterization of CG force fields is not trivial. For the CG study of complex systems such as CLs, the loss of atomistic detail is a real drawback. In fact, this difficulty is not specific to the system under study in this work, but it applies to classical atomistic and coarse-grained molecular modeling. Employing these methods relies on averaging out microscopic degrees of freedom. Electronic structure effects are not explicitly treated. These limitations are well apprehended (Markvoort, 2010). An adequate approach should incorporate essential physicochemical properties of interest, while ignoring certain less important details to keep the calculation computationally viable. 

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