Structural characteristics of 98-atom Co-Pt clusters

Abstract

The well-mixed morphology of 98-atom Co-Pt clusters is investigated. The global minimal structures of ComPt98-m (m = 1–97) clusters are optimized by adaptive immune optimization algorithm with inner cores (AIOA-IC) method based on the many-body Gupta potential. In Co-poor regions, the clusters are found to adopt face-centered cubic (fcc) and stacking-fault fcc (sf-fcc) motifs while in Co-rich regions, they present icosahedral motifs. Leary tetrahedron (LT) appears to be the dominant motif among all compositions. A Td point group is found in Co80Pt18 cluster, and the construction method for the Td LT is proposed starting from a regular tetrahedron. Moreover, the Co-Pt clusters favor well-mixed pattern except for Co-rich and Co-poor regions and the highest degree of mixing is at Co55Pt43, which is one of the 14 amorphous motifs but not LT motif. The phenomenon of atomic rearrangement is also reported.