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submitted on 06.05.2020 and posted on 08.05.2020by Mohammad Atif Faiz Afzal, Andrea Browning, Alexander Goldberg, Mathew
D. Halls, Jacob L. Gavartin, Tsuguo Morisato, Thomas
F. Hughes, David J. Giesen, Joseph E. Goose
Recent advances in
graphics-processing-unit (GPU) hardware and improved
efficiencies of atomistic simulation programs allow
the screening of a large number of polymers to predict properties that require
running and analyzing long Molecular Dynamics
(MD) trajectories of large molecular systems. This paper outlines an efficient MD
cooling simulation workflow based on GPU MD simulation and the refined
Optimized Potentials for Liquids Simulation (OPLS) OPLS3e force field to calculate glass transition temperatures (Tg)
of 315 polymers for which experimental values were reported by Bicerano.1 We observed good agreement of predicted Tg
values with experimental observation across a wide range of polymers, which
confirms the clear utility of the
described workflow. During the stepwise cooling simulation for the calculation
of Tg, a subset of polymers clearly showed an ordered structure
developing as the temperature decreased. Such polymers have a point of
discontinuity on the specific volume vs. temperature plot, which we associated
with the melting temperature (Tm). We demonstrate the distinction
between crystallized and amorphous polymers by examining polyethylene. Linear
polyethylene shows a discontinuity in the
specific volume vs. temperature plot, but we do not observe the discontinuity for branched polyethylene simulations.