Thermodynamics of a liquid microcluster

Abstract

A theory of surface tension is formulated for liquid microclusters which are so small that the homogeneous properties of the bulk liquid are not attained even at the center. The choice of the equimolecular dividing surface is made possible by employing a reference bulk liquid which possesses a different chemical potential from that of the real system. Cluster-size dependence of the surface tension is formulated in such a manner that the results of computer simulations for microclusters and for the bulk liquid may be employed, and it is found that for the size range relevant in nucleation the value of surface tension is appreciably greater than the bulk surface tension. The formalism is extended to noncritical microclusters, and the Gibbs-Thomson equation is derived in the present formalism to provide the size of a critical nucleus under a given supersaturation.