  The energy band gap structure and stability of (3,3) and (10,10) nanotubes
have been comparatively investigated in the frameworks of the traditional form
of the Su-Schrieffer-Heeger (SSH) model and a toy model including the
contributions of bonds of different types to the SSH Hamiltonian differently.
Both models give the same energy band gap structure but bond length distortions
in different characters for the nanotubes.
