Vapor phase nucleation: Molecular mechanisms for embryo development

Abstract

The special features that distinguish the present theory from previous ones are (1) its molecular formulation such that the physical clusters upon which it is based can be used to accurately evaluate the partition function of the full supersaturated vapor, and (2) the characterization of clusters by more parameters than molecular content i alone. Only one additional parameter is used, namely v but this is enough to allow a natural distinction (the valley and the evaporation boundary) between clusters that serve as embryos and those that do not. Furthermore the v parameter reveals the existence of an important additional mode of cluster variation, i.e., the collective relaxation of its radial density distribution toward the evaporation boundary. If the valley existed on both sides of the ridge this mode would be unimportant since the entire nucleation process, on both sides of the ridge, would be channeled along the axis of the valley, and a characterization of the cluster by i alone would be almost sufficient

Unfortunately, the nonexistence of the valley on the near side of the ridge has been documented by both Monte Carlo simulation and the MLDM method. Its absence on the near side has also been demonstrated by Talanquer and Oxtoby (20) using a density functional method.

Current and future work is and will be aimed at exploiting the full molecular nature of the theory.