Coarse-grained modeling of polyethylene melts: Effect on dynamics

Journal Article · Tue May 23 00:00:00 EDT 2017 · Journal of Chemical Theory and Computation

DOI:https://doi.org/10.1021/acs.jctc.7b00241· OSTI ID:1367349

Peters, Brandon L. ^[1]; Salerno, K. Michael ^[2]; Agrawal, Anupriya ^[3]; Perahia, Dvora ^[4]; Grest, Gary S.  ^[1]

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1. Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
2. U.S. Naval Research Lab., Washington, D.C. (United States)
3. Washington Univ., St. Louis, MO (United States)
4. Clemson Univ., Clemson, SC (United States)

The distinctive viscoelastic behavior of polymers results from a coupled interplay of motion on multiple length and time scales. Capturing the broad time and length scales of polymer motion remains a challenge. Using polyethylene (PE) as a model macromolecule, we construct coarse-grained (CG) models of PE with three to six methyl groups per CG bead and probe two critical aspects of the technique: pressure corrections required after iterative Boltzmann inversion (IBI) to generate CG potentials that match the pressure of reference fully atomistic melt simulations and the transferability of CG potentials across temperatures. While IBI produces nonbonded pair potentials that give excellent agreement between the atomistic and CG pair correlation functions, the resulting pressure for the CG models is large compared with the pressure of the atomistic system. We find that correcting the potential to match the reference pressure leads to nonbonded interactions with much deeper minima and slightly smaller effective bead diameter. However, simulations with potentials generated by IBI and pressure-corrected IBI result in similar mean-square displacements (MSDs) and stress autocorrelation functions G(t) for PE melts. While the time rescaling factor required to match CG and atomistic models is the same for pressure- and non-pressure-corrected CG models, it strongly depends on temperature. Furthermore, transferability was investigated by comparing the MSDs and stress autocorrelation functions for potentials developed at different temperatures.

• Research Organization: Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
• Sponsoring Organization: USDOE National Nuclear Security Administration (NNSA)
• Grant/Contract Number: AC04-94AL85000
• OSTI ID: 1367349
• Report Number(s): SAND-2017-6200J; 654461
• Journal Information: Journal of Chemical Theory and Computation, Vol. 13, Issue 6; ISSN 1549-9618
• Publisher: American Chemical Society
• Country of Publication: United States
• Language: English

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37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
36 MATERIALS SCIENCE