Work of cavity formation inside a fluid using free-energy perturbation theory

A semiempirical approach, based on both the scaled particle theory of hard particle fluids and free-energy perturbation methods, that predicts the work of formation of a cavity inside a model fluid is presented. The method is tested using the pure component Lennard-Jones fluid. A good agreement between values obtained via the theory and molecular simulation is observed even as the size of the cavity becomes larger than the effective diameter of Lennard-Jones particles. The method also yields reasonably accurate estimates when the pressure of the liquid is quite low, which is the case for liquids close to the coexistence line, or when the pressure is negative, which is the case when the liquid is metastable.