Au ₂₀ : A Tetrahedral Cluster

Photoelectron spectroscopy revealed that a 20-atom gold cluster has an extremely large energy gap, which is even greater than that of C ₆₀ , and an electron affinity comparable with that of C ₆₀ . This observation suggests that the Au ₂₀ cluster should be highly stable and chemically inert. Using relativistic density functional calculations, we found that Au ₂₀ possesses a tetrahedral structure, which is a fragment of the face-centered cubic lattice of bulk gold with a small structural relaxation. Au ₂₀ is thus a unique molecule with atomic packing similar to that of bulk gold but with very different properties.