Structural rigidity and low frequency vibrational modes of long carbon tubules

We have studied the low frequency vibrational modes and the structural rigidity of long graphitic carbon tubules consisting of 100, 200, and 400 atoms. Our calculations have been performed using an empirical Keating Hamiltonian with parameters determined from first principles. We have found the beam bending mode to be one of the softest modes in these structures. The corresponding beam rigity of a bucky tube is compared to an found to exceed the highest values found in presently available materials.