Theoretical study of a hypothetical metallic phase of carbon

We have studied the structural properties and electronic structure of a hypothetical, all-${\mathit{sp}}^2$ phase of carbon using the first-principles pseudopotential total-energy method. The phase, called bct-4 C, is found to be a low-compressibility metal. Because of the nearly perfect lattice match with the diamond (100) surface, we suggest that it may be possible to epitaxially grow bct-4 C on the diamond (100) surface.