Parameter passing between Molecular Dynamics and continuum models for droplets on solid substrates - The static case

TL;DR

This paper compares molecular dynamics and continuum models for droplets on substrates, focusing on interface tensions and disjoining pressure, and demonstrates good agreement in contact angle predictions when models are properly aligned.

Contribution

It introduces parameter-passing techniques that enable detailed comparison between molecular dynamics and continuum models for droplet equilibrium properties.

Findings

Molecular dynamics determines interface tensions and disjoining pressure.

Continuum models incorporate these parameters for accurate predictions.

Good agreement in contact angle dependence on droplet size.

Abstract

We study equilibrium properties of polymer films and droplets on a solid substrate employing particle-based simulation techniques (Molecular Dynamics) and a continuum description. Parameter-passing techniques are explored that facilitate a detailed comparison of the two models. In particular, the liquid-vapor, solid-liquid and solid-vapor interface tensions, and the Derjaguin or disjoining pressure are determined by Molecular Dynamics simulations. This information is then introduced into continuum descriptions accounting for (i) the full curvature and (ii) a long-wave approximation of the curvature (thin film model). A comparison of the dependence of the contact angle on droplet size indicates that the theories agree well if the contact angles are defined in a compatible manner.