Multiscale modeling of soft matter: scaling of dynamics

Fritz, Dominik; Koschke, Konstantin; Harmandaris, Vagelis; Vegt, Nico F. A. van der; Kremer, Kurt

doi:10.1039/c1cp20247b

Cited by 172 publications

(182 citation statements)

References 55 publications

(89 reference statements)

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“…In principle, the correspondence to real time within each model should be gauged against experiment or all-atom simulations. 33 For the MARTINI model, a speed-up of about a factor of 4 was found in liquid systems and lipid bilayers based on diffusion of solvent and lipids. 26 2.5.…”

Section: Interaction Sitesmentioning

confidence: 99%

MARTINI Model for Physisorption of Organic Molecules on Graphite

et al. 2013

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An extension to the MARTINI coarse-grained model is presented to describe the adsorption of organic molecules on graphite surfaces. The model allows the study of the dynamics of the preferential adsorption of long-chain organic molecules from solvent and the formation of ordered structures on the surface through self-assembly on the microsecond time scale. It was found that the MARTINI model, developed for self-assembling biomolecular systems in solution, could be extended to include two-dimensional selfassembly on a solid surface using a single recipe to determine the interactions of the existing bead-types with the new representation of graphite. The model was parametrized on adsorption enthalpies of small molecules from the gas phase and on wetting enthalpies of pure compounds. Three wetting enthalpies were determined experimentally to extend the range of chemical functionalities parametrized against. The model reproduces order− disorder transitions of hexadecane and hexadecanol and preferential adsorption of long-chain organic compounds from organic solvents, including the formation of lamellar arrangements on the surface.

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Section: Interaction Sitesmentioning

confidence: 99%

MARTINI Model for Physisorption of Organic Molecules on Graphite

et al. 2013

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“…icantly faster than in atomistic simulations [29][30][31][32][33][34][35][36]. To determine the dynamic scaling factor of the CG models we compare the MSD of the inner 24 methylene groups (4, 6, 8 or 12 beads) for CG models and the inner 24 carbon atoms for atomistic simulations for n=96 and 480 as shown in Fig.…”

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confidence: 99%

Resolving Dynamic Properties of Polymers through Coarse-Grained Computational Studies

et al. 2016

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Coupled length and time scales determine the dynamic behavior of polymers and underlie their unique viscoelastic properties. To resolve the long-time dynamics it is imperative to determine which time and length scales must be correctly modeled. Here we probe the degree of coarse graining required to simultaneously retain significant atomistic details and access large length and time scales. The degree of coarse graining in turn sets the minimum length scale instrumental in defining polymer properties and dynamics. Using linear polyethylene as a model system, we probe how coarse graining scale affects the measured dynamics. Iterative Boltzmann inversion is used to derive coarse-grained potentials with 2-6 methylene groups per coarse-grained bead from a fully atomistic melt simulation. We show that atomistic detail is critical to capturing large scale dynamics. Using these models we simulate polyethylene melts for times over 500 µs to study the viscoelastic properties of well-entangled polymer chains.Polymer properties depend on a wide range of coupled length and time scales, with unique viscoelastic properties stemming from interactions at the atomistic level. The need to probe polymers across time and length scales to capture polymer behavior makes probing dynamics, and particularly computational modeling, inherently challenging. With increasing molecular weight, polymer melts become highly entangled and the longtime diffusive regime becomes computationally inaccessible using atomistic simulations. In these systems the diffusive time scale increases with polymerization number N faster than N 3 , becoming greater than 10 10 times larger than the shortest time scales even for modest molecular weight polymers. While it is clear that the largest lengths scales of polymer dynamics are controlled by entanglements, the shortest time and length scales required to resolve dynamic properties are not obvious. This knowledge is critical for developing models that can transpose atomistic details into the long time scales needed to model long, entangled polymer chains.One path to overcoming this computational challenge is to coarse grain the polymer, reducing the number of degrees of freedom and increasing the fundamental time scale. The effectiveness of this process depends on retaining the smallest length scale essential to capturing the polymer dynamics. The process of coarse graining amounts to combining groups of atoms into pseudoatom beads and determining the bead interaction potentials [1,2]. Simple models like the bead-spring model [3], capture characteristics described by scaling theories, but disregard atomistic details and cannot quantitatively describe properties like structure, local dynamics or densities. Immense efforts have been made to systematically coarse grain polymers and bridge the gap of time and length scales while retaining atomistic characteristics [4]. One critical issue underlying the coarse graining process is the degree to which a polymer can be coarseA single C96H194 PE chain represented with in...

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“…Coarse-grained models that couple to the underlying atomistic descriptions are primarily used in modeling properties in polymeric systems, such as configurations and dynamics in the melt 11,[24][25][26][27] and solutions, 28,29 polymer brush conformations, 30 self-assembly kinetics, 31 etc. To our knowledge, there is only one prior study that has used multiscale modeling for a simplified system of nanocomposites focusing on how to improve the coarse-grained parameters to match nanoparticle distributions obtained by atomistic models.…”

Section: Introductionmentioning

confidence: 99%

Dynamics in coarse-grained models for oligomer-grafted silica nanoparticles

Hong

Chremos

Panagiotopoulos

2012

The Journal of Chemical Physics

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Effect of bidispersity in grafted chain length on grafted chain conformations and potential of mean force between polymer grafted nanoparticles in a homopolymer matrix J. Chem. Phys. 134, 194906 (2011) Coarse-grained models of poly(ethylene oxide) oligomer-grafted nanoparticles are established by matching their structural distribution functions to atomistic simulation data. Coarse-grained force fields for bulk oligomer chains show excellent transferability with respect to chain lengths and temperature, but structure and dynamics of grafted nanoparticle systems exhibit a strong dependence on the core-core interactions. This leads to poor transferability of the core potential to conditions different from the state point at which the potential was optimized. Remarkably, coarse graining of grafted nanoparticles can either accelerate or slowdown the core motions, depending on the length of the grafted chains. This stands in sharp contrast to linear polymer systems, for which coarse graining always accelerates the dynamics. Diffusivity data suggest that the grafting topology is one cause of slower motions of the cores for short-chain oligomer-grafted nanoparticles; an estimation based on transition-state theory shows the coarse-grained core-core potential also has a slowing-down effect on the nanoparticle organic hybrid materials motions; both effects diminish as grafted chains become longer.;

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Multiscale modeling of soft matter: scaling of dynamics

Cited by 172 publications

References 55 publications

MARTINI Model for Physisorption of Organic Molecules on Graphite

MARTINI Model for Physisorption of Organic Molecules on Graphite

Resolving Dynamic Properties of Polymers through Coarse-Grained Computational Studies

Dynamics in coarse-grained models for oligomer-grafted silica nanoparticles

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