Geometrical, electronic, and magnetic properties of small AunSc (n=1–8) clusters

Geometrical, electronic, and magnetic properties of the Sc-doped gold clusters, AunSc (n=1–8), have been studied using the density-functional theory within the generalized gradient approximation. An extensive structural search shows that the Sc atom in low-energy AunSc isomers tends to occupy the most highly coordinated position. The substitution of a Sc atom for an Au atom in the Aun+1 cluster markedly changes the structure of the host cluster. Moreover, we confirm that the ground-state Au6Sc cluster has a distortion to a lower D2h symmetry. The relative stabilities and electronic properties of the lowest-energy AunSc clusters are analyzed based on the averaged binding energies, second-order energy differences, fragmentation energies, chemical hardnesses, and HOMO–LUMO gaps. It is found that the magic Au3Sc cluster can be perceived as a superatom with high chemical stability and its HOMO–LUMO gap is larger than that of the closed-shell Zr@Au14 cluster. The high symmetry and spin multiplicity of the Au3Sc and Au6Sc clusters are responsible for their large vertical ionization potential and electron affinity. The magnetism calculations indicate that the magnetic moment of the Sc atom in the ground-state AunSc (n=2–8) clusters gradually decreases for even n and is completely quenched for odd n.