ALIGNMENT DEFECTS IN ZIGZAG AND ARMCHAIR CARBON NANOTUBULES

Forming a carbon cylinder by rolling a sheet of graphite causes alignm ent defects of orbitals with a consequent change of the total elastic energy. Using a Green's function technique and total-energy minimaliza tion of the one-dimensional unit cell, we obtain analytic expressions for the deformation potential energy and the densities of states. The calculated elastic coupling constants allow us to evaluate the gaps wh ich are in good agreement with experimental values.