Insight into the structural and electronic properties of Pd55-nNin (n=0-55) clusters: A density functional theory study

Abstract

The structural and electronic properties of the icosahedral Pd55-nNin (n=0-55) clusters have been investigated within the density functional theory. According to the calculated excess energy, we found that the core-shell Ni13@Pd42 cluster is the most stable structure, and Pd44Ni11 cluster possesses the highest relative stability among the random Pd55-nNin clusters. The calculated first-neighbor distances of Pd-Pd and Ni-Ni in Pd28Ni27 and Pd13Ni42 clusters are consistent with the experimental results. The electronic property analysis reveals that the interaction between Pd-4d and Ni-3d orbitals makes the main contribution and a strong d-d self-interaction among the Ni-3d. With an increasing number of Ni atoms, the d-band center of the surface Pd atoms shifts far away from the Fermi level, while the root mean squared d-band width broadens. This feature is also observed in the partial density of states of the surface Pd atoms. Through analyzing the Löwdin charge population, there is significant charge transfer from Ni atoms at the top sites of surface to Ni atoms in the core, and partial charge is transferred from Pd to Ni in the bimetallic cluster.