Monte Carlo Test of the Classical Theory for Heterogeneous Nucleation Barriers

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

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