Theoretical phonon dispersion of armchair and metallic zigzag carbon nanotubes beyond the adiabatic approximation

Abstract

AbstractThe dynamic corrections to the phonon dispersion of armchair and metallic zigzag carbon nanotubes are studied systematically within a non‐orthogonal tight‐binding model. These corrections were found to be important in the vicinity of the Kohn anomaly of the phonon dispersion at two points of the Brillouin zone. The first point is the zone‐centre and the dynamic corrections are large for the longitudinal optical phonons, which give rise to the G−‐band in the Raman spectra. The obtained frequencies of these phonons for a large number of metallic nanotubes are in good agreement with previous estimations and available experimental data. The second point is inside the zone for armchair nanotubes and at the zone centre for zigzag nanotubes. In this case, the dynamic effects are also studied and discussed in view of their importance for modelling of double‐resonance scattering processes.