Minimum free-energy pathway of nucleation.

Nucleation in a two-component incompressible system was studied by examining the topology of the free-energy landscape. The properties of a single nucleus during nucleation were derived from the minimum free-energy pathway (MFEP) within the Cahn-Hilliard continuum theory of nucleation. MFEPs were computed using the string method. In particular, we have provided a detailed description of the nucleation process for a regular solution (T/T(c) = 0.8656) for increasing supersaturation up to the spinodal line. Two original results were found in terms of the physics of nucleation. A universal two-step behaviour was found whatever the supersaturation: nuclei sharply enrich up to equilibrium and then grow. Embryos show diffuse interfaces along the MFEP. The width of interfaces quickly saturates to its value at the critical nuclei and stays constant afterwards.