Effect of conjugation on the vibrational modes of a carbon nanotube dimer

First Principles simulation studies using the density functional theory have been performed to investigate the ef-fect of conjugation on vibrational modes when two CNTs of different chiralities are held together to constitute an inhomogeneous dimer. Raman Spectra of a (5, 0) CNT; a (6,0) CNT and a (5,0)(6,0) CNT dimer comprising of parallel standing (5,0) and (6,0) CNTs held by weak Van der Waals were simulated. Various vibrational modes in different frequency regions have been discussed in detail. A red shift is observed overall that clearly affirms the stability and existence of the structure formed by conjugation of CNTs. In the RBM (Radial Breathing Mode) region, additional peaks can be seen arising out of the coupled vibrations. D-band peaks of the dimer cover the D-band peaks of both the CNTs as disorder in the constituents reflects in its constitution. In the G-band region of the dimer spectrum, a low wavelength component with Lorentzian shape and a weak high wavelength component with a Breit Wigner Fano (BWF) kind of line-shape suggest metallic nature of the inhomogeneous CNT dimer. (c) 2020 Elsevier B.V. All rights reserved.