The Study Of Structural Properties Of Global Minimum Co_n, Rh_n (n=3-56) Clusters By Using Genetic Algorithm

Clusters are composed by two too thousands of atoms (moleculars) by physical or chemical binding energy. The global minimum structure properties of a cluster is no doubt the most important one to study their other chemical and physical behavior. In this paper, we used a semi-empirical many-body potential combined with the Genetic Algorithm to perform a systematic study for the global minima of Con,Rhn(n=3-56) clusters.For cobalt cluster during the size of n=3-56, we found there exists structural competition between the icosahedron-like and the fcc-like. For the cases n≥39, the icosahedral growth model presents obviously. 13, 19, 23, 38, 55 are the magic numbers of the cobalt clusters. By analyzing the average coordination number and the average nearest-neighbor distance of these clusters, we studied their magic structures. It is noticeable that the inner atoms could enhance both symmetry and stability of the clusters. For Con(n=3-56) cluster, the magic structure is determined mainly by its geometrical structure.Compared the results of rhodium and cobalt clusters in the size of n=3-56, we got important conclusions as follow:Most of their geometric structures were similar except a few cases in the range of n=18-40. In this paper, we found there exists structural competition between the icosahedron-like and the fcc-like. For n≤24, the ground geometric structures transform from the close-packing to the icosahedron-like. Both Rh38 and Co38 are the fcc-like structure with Oh symmetry. In the cases of n≥39, the icosahedral growth model presented obviously for this two types of...