Abstract
The dependence of the breathing-like phonon modes (BLM) and tangential-like phonon modes (TLM) of individual, finite and infinite bundles of double-walled carbon nanotubes (DWCNTs) as a function of the relative lengths of the inner (L-i) and outer (L-o) tubes is calculated by using the spectral moments method in the framework of the bond-polarization theory. Depending on the relative lengths of the inner (L-i) and outer (L-o) tubes, additional modes are evidenced in the BLM region. These modes must be considered in the analysis of the experimental data.