Systematic time-scale-bridging molecular dynamics applied to flowing polymer melts

TL;DR

This paper introduces a thermodynamically guided, efficient coarse-graining method for simulating the dynamics of polymer melts under flow, enabling predictions beyond linear response and providing steady-state results.

Contribution

It presents a novel systematic time-scale bridging approach combining thermodynamics and Monte Carlo--molecular dynamics for complex fluid simulations.

Findings

Predicts structural and material functions beyond linear response

First steady state equibiaxial simulation results for polymer melts

Method is simple to implement and computes time-dependent behavior

Abstract

We present a novel thermodynamically guided, low-noise, time-scale bridging, and pertinently efficient strategy for the dynamic simulation of microscopic models for complex fluids. The systematic coarse-graining method is exemplified for low-molecular polymeric systems subjected to homogeneous flow fields. We use established concepts of nonequilibrium thermodynamics and an alternating Monte-Carlo--molecular dynamics iteration scheme in order to obtain the model equations for the slow variables. For chosen flow situations of interest, the established model predicts structural as well as material functions beyond the regime of linear response. As a by-product, we present the first steady state equibiaxial simulation results for polymer melts. The method is simple to implement and allows for the calculation of time-dependent behavior through quantities readily available from the nonequilibrium steady states.