The assumptions of homogeneous nucleation theory are examined for the liquid-vapor transition of a Lennard-Jones fluid. Approximate solutions of the first Yvon-Born-Green integro-differential equation in a spherically symmetric and finite volume provide the dependence of the density profile of a small droplet on temperature and supersaturation. The structure provides a mechanical approach via the pressure tensor to the interfacial properties. Classical thermodynamic and statistical mechanical expressions for the surface tension are compared. This approach allows the calculation of the free energy of formation of a droplet from a metastable vapor, avoiding most of the usual assumptions of homogeneous nucleation theory. These theoretical results, which are tested by comparison with molecular dynamics simulations, indicate that the droplet size dependence of the interfacial free energy is sufficiently strong that, for the state points considered, the free energy barrier prior to the nucleation is absent. The atomic kinetics of condensation are examined visually using molecular dynamics temperature quenching experiments, providing insight into the kinetic hindrance of the nucleation process. Recent theoretical and simulation studies of cluster structure and solvation in ionic solutions are discussed.
|Title of host publication||Crystallization as a Separations Process|
|Number of pages||19|
|Publication status||Published - 1990|
|Series||A C S Symposium Series|