On radial breathing vibration of carbon nanotubes

The study aims at exploring the RBM (radial breathing mode) frequencies and mode shapes of various carbon nanotubes (CNTs) using a modified molecular structural mechanics (MSM) model. The focus of the work is placed upon studying the characteristics of the RBM-like modes of the CNTs resulted from their large diameter-length aspect ratio and/or asymmetric atomic configuration. By the approach, their dependence on the layer number, aspect ratio and chirality of the CNTs and temperature is also assessed. The validity of these calculated results is extensively confirmed through comparison with the literature theoretical and experimental data. Simulation results show that an additional layer of CNTs would not have significant impact on the associated RBM frequencies. In addition, asymmetric, non-purely radial RBM modes are observed in the chiral CNTs mainly because of their non-axisymmetric atomic structure. Besides, as the aspect ratio becomes larger than about 1.25, the original, standard RBM mode would be transformed into an RBM-like mode.