Theoretical resonant Raman spectra of nanotube (7,0) with point defects

The Raman spectra of the nanotube (7,0) with point defects (monovacancy, divacancy, and Stone-Wales defect) were simulated in order to derive spectroscopic signatures of defective nanotubes. First, we calculated the electronic band structure and the phonon dispersion of the defective nanotubes using supercells within a non-orthogonal tight-binding model. We found that new optical transitions and Raman-active phonons appeared in comparison with the perfect nanotube. Secondly, we calculated the resonance Raman excitation profile for all Raman-active phonons of the defective nanotubes and simulated their Raman spectra at specific laser excitation energies. The predicted high-intensity Raman lines can be used as spectroscopic signatures of the defective nanotubes.