Generating multi-chain configurations of an inhomogeneous melt from the knowledge of single-chain properties

TL;DR

This paper presents a method to generate nearly equilibrated multi-chain configurations of inhomogeneous polymer melts using single-chain properties and packing algorithms, improving initial states for molecular dynamics simulations.

Contribution

It introduces a novel approach combining mean-field single-chain data with packing algorithms to better approximate intermolecular correlations in confined polymer systems.

Findings

The method effectively restores intermolecular correlations near solid substrates.

Configurations generated serve as improved starting points for molecular dynamics.

The approach reduces density fluctuations and enhances simulation accuracy.

Abstract

Mean-field techniques provide a rather accurate description of single-chain conformations in spatially inhomogeneous polymer systems containing interfaces or surfaces. Intermolecular correlations, however, are not described by the mean-field approach and information about the distribution of distance between different molecules is lost. Based on the knowledge of the exact equilibrium single-chain properties in contact with solid substrates, we generate multi-chain configurations that serve as nearly equilibrated starting configurations for molecular dynamics simulations by utilizing the packing algorithm of Auhl and co-workers [J. Chem. Phys. 119, 12718 (2003)] for spatially inhomogeneous systems, i.e., a thin polymer film confined between two solid substrates. The single-chain conformations are packed into the thin film conserving the single-chain properties and simultaneously minimizing local fluctuations of the density. The extent to which enforcing the near-incompressibility of a dense polymer liquid during the packing process is able to re-establish intermolecular correlations is investigated by monitoring intermolecular correlation functions and the structure function of density fluctuations as a function of the distance from the confining solid substrates.