Molecular model for ice clusters in a supersaturated vapor

Abstract

A molecular model previously applied to prenucleation water clusters is used to examine ice I_h embryos. The canonical partition function is evaluated for clusters having from 6 to 64 water molecules. The intermolecular vibrational free energies are extrapolated to clusters containing up to 120 molecules and free energies of formation, nucleation rates, and critical supersaturation ratios are calculated and compared with experiment. For the clusters studied, the ice I_h structure appears to be much less stable at all temperatures than the more spherical clathratelike cluster.