Possible Ground-State Structure of Au26: a Highly Symmetric Tube-Like   Cage
  A surprising stability of the tube-like AuN (N = 26-28) has been shown using the scalar relativistic all-electron density functional theory calculations, forming another powerful candidate for the lowest-energy AuN competing with those previously suggested space-filled structures. Unlike the icosahedral "golden" fullerene Au32, these tube-like gold clusters may be closely related to the synthesized single-wall gold nanotubes (SWGNT). The ground-state Au26 has a hollow tube-like structure constructed from the (6, 0) SWGNT, yielding a high-symmetry D6d cage, based upon which the most stable Au27 and Au28 can be obtained by capped one and two atoms, respectively. 
Wei Fa and Jinming Dong