Coarse-Grained Modeling of Polyethylene Melts: Effect on Dynamics

Peters, Brandon L.; Salerno, K. Michael; Agrawal, Arpit; Perahia, Dvora; Grest, Gary S.

doi:10.1021/acs.jctc.7b00241

Cited by 52 publications

(70 citation statements)

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“…We would like to stress the fact that in this study, we observe only classical diffusion, unlike some previous studies. In [27] and [31], polymer melts with CG particles composed of three CH2 monomers, as considered here, were studied. Sub-diffusion was observed for the quantity D h for simulation times up to and exceeding our simulation time of 250 ns (although the polymer lengths were at least double ours).…”

Section: Simulation Resultsmentioning

confidence: 99%

Comparison of modern Langevin integrators for simulations of coarse-grained polymer melts

2019

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For a wide range of phenomena, current computational ability does not always allow for fully atomistic simulations of high-dimensional molecular systems to reach time scales of interest. Coarse-graining (CG) is an established approach to alleviate the impact of computational limits while retaining the same algorithms used in atomistic simulations. It is of importance to understand how algorithms such as Langevin integrators perform on nontrivial CG molecular systems, and in particular how large of an integration time step can be used without introducing unacceptable amounts of error into averaged quantities of interest. To investigate this, we examined three different Langevin integrators on a CG polymer melt: the recently developed BAOAB method by Leimkuhler and Matthews [17], the Grønbech-Jensen and Farago method [12], or G-JF, and the frequently used Brünger-Brooks-Karplus integrator [6], also known as BBK. We compute and analyze key statistical properties for each. Our results indicate that the three integrators perform similarly when using a small friction parameter; however, outside of this regime the use of large integration steps produces significant deviations from the predicted diffusivity and steady-state distributions for all integration methods examined with the exception of G-JF.2010 Mathematics Subject Classification. 82C31; 82C80; 82D15.

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Section: Simulation Resultsmentioning

confidence: 99%

Comparison of modern Langevin integrators for simulations of coarse-grained polymer melts

2019

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“…It is worth noting that scaling factors are temperaturedependent quantities, and increase with decreasing temperatures. 31,32 Consequently, the timescales reported herein represent a lower bound on experimental timescales.…”

Section: Methodsmentioning

confidence: 81%

Polymer Nucleation under High-Driving Force, Long-Chain Conditions: Heat Release and the Separation of Timescales

Hall¹,

Percec²,

Klein³

2018

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<p>This study reveals two important features of polymer crystal formation at high-driving forces in entangled polymer melts based on molecular dynamics simulations of polyethylene, a prototypical polymer. First, in contrast to existing literature on small-molecule crystallization, it is demonstrated that the heat released during polymer crystallization does not appreciably influence molecular-level structural details of early-stage, crystalline clusters (i.e., polymer crystal nuclei). Second, it is revealed that early-stage polymer crystallization (i.e., crystal nucleation) can occur without substantial chain-level relaxation and conformational changes, which is consistent with previous experimental work and yet in contrast to many previous computational studies. Given the conditions used to process polyethylene, the separation of timescales associated with crystallization and chain-level processes is anticipated to be of substantial importance to processing strategies. This study thus provides insights that highlight new research directions for understanding polymer crystallization under industrially-relevant conditions while also providing guidance as to how this work can be undertaken.</p>

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“…• La masse volumique n'est pas correctement reproduite sans un ajustement fin à la main [36,61]. En regroupant à l'instant t toutes les forces f i (t) dans un unique vecteur F ref t de dimension 2 3N , les équations de la DPD peuvent se réécrire sous la forme…”

Section: Etat De L'art Et Problématiqueunclassified