Abstract
A microscopic theory is presented to explain how the melting point in metallic small particles is dependent on size. The systems are described by an effective pair interaction of the Gaussian type, constructed to give the basic thermodynamic properties in the bulk metal at low temperatures. The thermodynamic melting temperature, at which the difference between the total Helmholtz free energy of a solid particle and that of a liquid particle of the same mass vanishes, is used as a criterion of the actual melting point in small particles. The variational principle based on the Gibbs-Bogoliubov inequality is used to calculate the Helmholtz free energies of both phases. Applications to the FCC metals Al, Pb and Ag are made and the calculated size dependences of the melting points are similar for all these metals. The result for Pb is in reasonable agreement with experimental data.