Density functional study of Al-doped Au clusters

The equilibrium geometries and electronic properties of AunAl, up to n = 13, have been systematically investigated using the density functional theory. The results show that, for the AunAl clusters, two patterns are identified. Pattern one (n = 2, 3, 8), the lowest-energy geometries prefer two-dimensional structures. Pattern two (n = 4 - 7, 9 - 13), the lowest-energy geometries prefer three-dimensional structures. According to the analysis of the binding energy and the fragmentation energy, AunAl clusters with odd n are found to be more stable than those with even n. The same trend of alternation can be illuminated according to the computational results in the HOMO-LUMO gap, the ionization potential, and the electron affinities. The Al atom not only changes the structures of pure gold clusters, but also enhances their stabilities. NBO analysis indicates 6s orbital of Au atom hybridizes with 3 porbital of Al atom.