Ab initio calculations of structures and properties of diamond-like phases, obtained from nanotubes and 3D-graphites

Theoretical analysis of structures and calculations of properties of diamond-like phases obtained from carbon nanotubes and three-dimensional graphites are performed. As a result of the analysis, the possibility of the stable existence of thirteen phases in which all carbon atoms are in crystallographically equivalent positions was established. Using the density functional theory method in the local density approximation, for all phases geometrically optimized structures and structural characteristics, sublimation energy, bandgap and hardness are calculated. It was established that the properties of these phases can vary over a wide range.