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 ΔFₕₑₜ*, which needs to be overcome for the formation of sphere-cap-shaped nucleation seeds, is smaller than the barrier ΔFₕₒₘ* 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 ΔFₕₒₘ* and ΔFₕₑₜ* 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≤ΔFₕₒₘ*/kBT≤200) if (independently estimated) line tension effects are considered.