A superhard carbon allotrope with cage structure: oS44-carbon

First-principles calculations are applied to investigate a new carbon allotrope, denoted oS44-carbon, with orthorhombic symmetry and Cmmm space group. This fully sp3-hybridized bonded carbon network resembles an orderly stack of hexagonal prisms and two types of cages. The total energy is lower, and the thermodynamic stability is better, for oS44-carbon than synthesized T-carbon and supercubane. The dynamic stability and mechanical stability of...