Structural evolution of medium-sized Pdn(n=15–25) clusters from density functional theory

Four types of possible structural motifs of the medium-sized Pdn (n=15–25) clusters i.e., fcc like, decahedron based, icosahedron based, and prolate ellipsoid based, have been generated from an empirical genetic algorithm search and further investigated using spin-polarized density functional theory calculations. fcc-like structures based on Pd19 octahedron dominate the growth pathway of Pdn clusters (n=15–23). For larger clusters such as Pd24 and Pd25, a prolate ellipsoid-based geometry and a structure consisting of three interpenetrating decahedra are energetically favorable, respectively. The size-dependent cluster properties as well as the correlation between electronic properties and cluster geometry are also discussed, suggesting a particular stability cluster at Pd19 with a fcc-like octahedron structure.