Competition between face-centered cubic and icosahedral cluster structures

The binding energy of atoms in icosahedral and face-centered-cubic clusters is calculated numerically for pairwise Morse-potential interactions between atoms and for clusters containing from 561 to 923 atoms, which corresponds to gradual filling of the sixth layer of the icosahedral cluster. Perturbation theory is used to calculate the cluster binding energy, in which the small parameter is the ratio of the interaction energy between non-nearest neighbor atoms to the interaction energy between nearest neighbors. Values of the Morse interaction potential parameter are found for which the energies of clusters with different structures coincide. Under the conditions used in these computations, the strain energy of a cluster can be neglected. Although the contribution of the interaction energy between non-nearest neighbors to the total cluster energy is small, it turns out to be important in finding the level crossing parameter. Zh. éksp. Teor. Fiz. 112, 1082–1090 (September 1997)