Control of Electric Dipole Moment using Deformation induced by Functionalization of (5, 0) Zigzag Carbon Nanotubes as Gigahertz Oscillators

Electric dipole moment (EDM) required for the relative motion of carbon nanotube (CNT) walls in nanoelectromechanical systems (NEMS) such as actuators and oscillators is studied by functionalization. Pristine (5, 0) zigzag carbon nanotube with little inherent electric dipole moment (ì) were deformed by adding three –OH functional groups to its end rims. The properties of eight yielded isomers are studied. The Gibbs free energy calculations demonstrate that the eight structures are more stable than pristine CNT. The induced deformation resulted in charge imbalances which developed large electric dipole moments for each case. The values of dipole moments produced for all cases are calculated. The bandgap energy, conductivity, density of state (DOS) and IR spectra of these structures are also computed and analyzed. The study revealed that the location of the –OH positioning (site selectivity) which gives rise to different degrees of deformation has a significant impact on all of the above parameters, especially the magnitude and direction of the electric dipole moment. The functionalization produced large ì of about 6.9 D for 60 carbon atoms nanotube which is higher than in the previous study. Applying an external electric field to the isomers causes the CNTs with large dipole moments to either get attracted or repelled and hence physical movement or oscillation of the nanotube occurs. The frequency of this oscillation is in gigahertz scale.