Monte Carlo Test of the Classical Theory for Heterogeneous Nucleation Barriers

TL;DR

This study uses Monte Carlo simulations to test the classical theory of heterogeneous nucleation barriers, confirming its validity at nanoscopic scales when line tension effects are included.

Contribution

It provides the first computational validation of the classical heterogeneous nucleation theory at nanoscopic scales using Monte Carlo methods.

Findings

Classical theory holds for nanoscopic nucleation seeds when line tension is considered.

Simulation results match theoretical predictions for free energy barriers.

The study confirms theory applicability for barriers between 20 and 200 kBT.

Abstract

Flat walls facilitate the condensation of a supersaturated vapor: Classical theory of heterogeneous nucleation predicts that the free energy barrier $\Delta F_{\rm het}^*$ which needs to be overcome for the formation of sphere-cap shaped nucleation seeds is smaller than the barrier $\Delta F^*_{\rm hom}$ for spherical droplets in the bulk by a factor $0<f(\theta)<1$, which only depends on the contact angle $\theta$. In this letter we compute both $\Delta F^*_{\rm hom}$ and $\Delta F^*_{\rm het}$ from Monte Carlo simulations and test the theory for the lattice gas model (for which $\theta$ can be readily controlled). Even though the theory is only based on macroscopic arguments, it is shown to hold for experimentally relevant nanoscopic nucleation seeds ($20\leq\Delta F^*_{\rm hom}/k_BT\leq 200)$ if (independently estimated) line tension effects are considered.