Thermodynamic stability of discrete fully coordinated SiO2 spherical and elongated nanocages

Atomically well-defined discrete fully coordinated spherical and elongated nanocages constructed from SiO2 are shown, via density functional calculations, to be structurally stable. Generally the spherical nanocages are energetically preferred over the elongated nanocages. With increasing size, both types of nanostructures are shown to be increasingly thermodynamically stable with respect to known terminated silica nanostructures; and bulk alpha-quartz. The structural and low-energy cluster growth characteristics of SiO2 are compared with that of carbon nanostructures showing intriguing correspondences.