A density functional theory study of structural, electronic and optical properties of 9-atom silver‒copper clusters

Abstract In this paper, the structural, electronic, optical, Raman and vibrational properties of 9-atom silver‒copper bimetallic clusters are investigated using density functional theory. The results show that the lowest energy structures of pure Ag9, Ag8Cu1, Ag7Cu2, Ag2Cu7, and Ag1Cu8 clusters are made up of two pentahedra and one tetrahedron, the lowest energy structure of the Cu9 cluster is four tetrahedra capping a hexahedron, and the shapes of the remaining clusters differ from pure Ag9 and Cu9 clusters. In the lowest energy clusters, the Ag5Cu4 and Ag2Cu7 clusters are magic clusters and the Ag5Cu4 cluster has the highest electronic stability. The optical peaks of Ag9 and Cu9 clusters appear in their experimental spectra, respectively, and the blueshift appears in the optical spectra of all clusters (except Ag2Cu7-I and Ag1Cu8-I) compared with the Ag9-I and Cu9-I clusters. The Raman peaks and vibrational peaks of 9-atom silver‒copper bimetallic clusters give some important vibration information.