Geometrical structures of trimetallic Ag–Pd–Pt and Au–Pd–Pt clusters up to 147 atoms

Abstract

The core-shell morphologies of (PdPt)coreAgshell and (PdPt)coreAushell up to 147 atoms are investigated. The structural optimization of M–Pd–Pt (M = Ag or Au) is carried out by using adaptive immune optimization algorithm with constructed inner cores (AIOA-IC), which is described by the many-body Gupta potential. Results show that in Ag-rich AgnPd12Pt12 (n = 1–60) clusters, amorphous motifs with icosahedral fragments are the dominant motifs. However, in Au-rich AunPd12Pt12 clusters, icosahedra are the dominant motifs, which are competitive with decahedra in this size range. Furthermore, for the 100- and 147-atom M–Pd–Pt clusters, there exists significant structural difference. On the other hand, the atomic distribution of M–Pd–Pt clusters is analyzed by the order parameter and the number of bonds. Results show that Pd atoms in AgnPd12Pt12 clusters have more mixed pattern with Ag and Pt atoms than in AunPd12Pt12 clusters. It is further explained by surface energy, atomic radius, and cohesive energy.