First Principle Calculation on Au n Ag 2 ( n = 1∼4) Clusters

The first-principles method based on density-functional theory is used to investigate the geometries of the lowest-lying isomers of AunAg2 (n = 1~4) clusters. Several low-lying isomers are determined, and many of them in electronic configurations with a high spin multiplicity. The stability trend of Ag-doped Aun clusters is compared to that of pure Aun clusters. Our results indicate that the inclusion of two Ag atoms in the clusters lowers the cluster stability, indicating higher stability as the structures grow in size. The bigger energy difference between the Aun and AunAg2 curves as the structures grows in size. This information will be useful to understanding the enhanced catalytic activity and selectivity gained by using silver-doped gold catalyst.