  Since the discovery of the fullerene C60, many very interesting structures
have been proposed, such as Ti8C12, Au20, Au32, Au42, TM@Sin, Eu@Si20, B80, and
B_{40}^{-/0}. Here, an exceptionally stable hollow cage containing 20 scandiums
and 60 carbons was identified. This Sc20C60 molecular cluster has a Th point
group symmetry and a volleyball-like shape, that we refer to below as
Volleyballene. Electronic structure analysis shows that the formation of
delocalized {\pi} bonds between Sc atoms and neighboring five-membered carbon
rings is crucial for stabilizing the cage structure. A relatively large
HOMO-LUMO gap was found. The results of vibrational frequency analysis and
molecular dynamics simulations also demonstrate that this Volleyballene
molecule is exceptionally stable.
