Change in the electronic spectrum of a carbon nanotube during elastic deformation and the relative shear of atomic sublattices

The energy spectrum of the $\pi$ electrons of a single-layer carbon nanotube is theoretically studied as a function of the elastic strain obtained during uniaxial tension-compression or torsion of the nanotube. The change in the energy spectrum during atomic restructuring of the nanotube is investigated. The energy gap in the spectrum of the carbon nanotube is calculated as a function of the type of deformation.