Microscopic capillarity approximation: Free energies of small clusters

Free energies of crystalline microclusters containing 2⩽i⩽100 atoms as well as the bulk chemical potential and surface free energy of a microscopic fcc crystal are calculated for a model substance exhibiting a pairwise additive potential energy and only nearest neighbor interactions. These results are used to test various existing approximations for cluster free energy. An alternative treatment of small clusters is suggested. This microscopic capillarity approximation gives an improved description of the free energy of small clusters, at the expense of requiring knowledge of the free energy of the trimer.