TD-carbon: A new face-centered cubic carbon allotrope

A new allotrope with sp- and sp3- hybridized bonds has been predicted by first-principles calculations. This allotrope is formed by interweaving the structures of T-carbon and diamond, thus termed TD-carbon. The energy stability, thermodynamic stability and dynamic stability of TD-carbon have been verified through calculating the total energy, ab initio molecular dynamics simulation, and phonon spectra as well as elastic constants, respectively. TD-carbon is a semiconductor with a direct band gap of 2.82 eV and a low density of 0.673 g/cm3. Importantly, it absorbs visible light more easily than TiO2. These results suggest that TD-carbon is a potential functional material for optoelectronic devices, hydrogen storage and aerospace materials.