Structural, electronic, and optical properties of the Ag-Cu clusters with the equal number atoms

The structural, electronic, and optical properties of the AgnCun (n = 7 -14) clusters with the equal number of the Ag and Cu atoms are system-atically investigated by using the density functional theory method. The results indicate that as n is 9, the structures of the Ag-n Cu-n clusters begin to form the icosahedral core, and most Ag-Cu clusters with icosahedral cores have high stability. The Ag8Cu8 cluster has the highest mixing degree. The Ag10Cu10 cluster has relatively high energetic and electronic stability. For the density of states at the Fermi level, the Ag7Cu7, Ag8Cu8, Ag9Cu9, Ag10Cu10, and Ag14Cu14 clusters are mainly contributed by Cu atoms, while the Ag11Cu11, Ag12Cu12, and Ag13Cu13 clusters are mainly contributed by Ag atoms. Interestingly, the Cu-16-II cluster is magnetic. The absorption spectra of the AgnCun clusters are red-shift comparing with the pure Ag-2, clusters, but they are blue-shift comparing with the pure Cu-2, clusters. The absorption properties of the AgnCun clusters in the visible region are better than the pure clusters.