Bicanonical ensemble Monte Carlo simulation of water condensation in the field of crystal lattice defects

Abstract

The free energy, formation work and entropy dependences for water condensate formed from the vapor over the defect-free and containing surface defects basal face of β-AgI crystal at initial stage of condensation at temperatures of 260 K and 400 K are calculated using the bicanonical statistical ensemble method, with Ewald summation for long-range electrostatic and polarization interactions with the substrate. The effect of surface defects in form of rectangular “towers” as a part of regular structure on the stability of condensed phase embryos is investigated. In contrast to small-scale structures, relatively larger coarse-grained nanostructure of crystal surface demonstrates an unconditional advantage in the ability to stimulate condensation compared to defect-free surface. The formation of condensed phase embryos on the surface with multiple defects begins at vapor pressures 5–6 orders of magnitude lower than that on corresponding defect-free surface, and this effect is resistant to temperature variations. The condensate on the surface of the crystal is thermodynamically stable, both on defect-free and nanostructured surfaces, with the exception of short initial stage of the monomolecular film on the defect-free surface.