Structural patterns of unsupported gold clusters

The structure of metal clusters is essential to predict many of their physical and chemical properties. Using first principles density functional calculations it was recently found that even ‘magic’ cluster sizes, for which very compact and symmetric structures exist, have lower-energy ‘disordered’ structures. The origin of these structures was shown to lie in the non-pairwise metallic interactions; while the compact ordered geometries are very stable for pair potentials, they are de-stabilized by the tendency of metallic bonds to contract at the surface. Here we identify important patterns of the resulting ‘amorphous’ structures, showing why they are optimal for the metallic potential, and how they can be used to predict structures for other cluster sizes.