Figure 39: Plot energy versuskxandky(2 dimensions).7.2.5 Carbon nanotubes
Carbon nanotubesare made of a sheet ofgraphenerolled up into a tube. There are three different
types of carbon nanotubes, as we can see in fig. 40.
Figure 40: Different types of carbon nanotubes.- Armchair: Looks like an armchair.
- Zig-Zag: Going around (along the diameter) the tube it makes zig-zag.
- Chiral: Atomic rows do not go straight on the tube, they twist around (chiral can vary).
Carbon nanotubes can also have different diameters. A terminology to specify what kind of nanotube
we have is to take a plane of graphene like in fig. 41. We choose an origin and count along over
the primitive lattice vectors to another point of the lattice with an equivalent site. Then we cut the