Diffuse interface theory for homogeneous vapor condensation

The excess free energy of nuclei is evaluated in terms of a characteristic interface thickness related to bulk physical properties. A curvature correction to the surface tension of nuclei up to second order in terms of the characteristic thickness is obtained. A nucleation theory free of adjustable parameters is presented. The predictions are compared with experiments on homogeneous condensation of nonpolar (nonane, toluene, Ar), polar (water, alcohols), and metal (Fe, Pb, Hg, Cs) vapors. For molecular liquids the applicability of the theory correlates with the surface entropy. In case of nonpolar, weakly polar, and metallic substances the experiments are described better than by the classical theory.