Structural transition and magnetic properties of ComPtn (m+n=38) clusters

The ground state structures of ComPtn (m+n=38) clusters are obtained by a genetic algorithm with a Gupta-like many-body potential, and further optimized using the density functional theory. The structure of pure atomic clusters Co38 and Pt38 is truncated octahedron. For the clusters with n=1, 2 and 34-37, their structures are slightly distorted configuration of Co38 and Pt38. The structures of all the other bimetallic clusters are defective pattern based on icosahedrons. Segregation effect can be seen in the ground structures of bimetallic clusters. The Pt atom prefers to locate on the surfaces of these clusters. The cluster with n=3, 5, 23, 29, 33, they are relatively more stable than their neighbors. The magnetic moment of Co38 is in agreement with experiment. The nonzero moment of Pt38 cluster is found. Compared with Co38, the introduction of Pt atom dramatically reduces the total magnetic moments of ComPtn clusters.