First-Principles Study of Carbon Nanotube Solid-State Packings

In the framework of the density functional theory, we study the energetics and geometry of three-dimensional solids made of single-shell carbon nanotubes. Amongst the investigated forms, a hexagonal packing with an interdistance of 3.14 Angstrom between the tubes is found to be the most stable. We find that the matching of atomic positions between nearest-neighbour tubules is an important contribution to the intertubule cohesive energy, and we explore the consequences of this fact on packing of non-hexagonal tubules. The ab initio calculation of the electronic properties of our most stable hexagonal packing reveals that the zero-gap feature of the isolated tubule could eventually be conserved in solid-state environment.