Effect of different defects on natural frequency of single walled carbon nanotubes using molecular structural mechanics

This investigation presents the effect of different defects on natural frequency of single walled carbon nanotubes. Molecular mechanics model is used to simulate SWCNTs. To investigate the natural frequency of carbon nanotubes, an equivalent beam model is first constructed. The molecular mechanics potentials in a C–C covalent bond are transformed into the form of equivalent strain energy stored in a three dimensional (3D) virtual beam element connecting two carbon atoms. Then, the equivalent stiffness parameters of the beam element can be estimated from the force field constants of the molecular mechanics theory. Defects occur during growth process, so determining natural frequency of defective CNTs is very important for improving their performance. Zigzag and armchair carbon nanotubes with different chiralities are considered. Accuracy of modeling is verified by comparing our results of predicting ideal SWCNT natural frequency, with results of past studies. Effects of diameter and boundary conditions on natural frequency of perfect and defective SWCNTs are investigated. For defects simulation, related elements are omitted in frame like model. Our results indicate that by increasing diameter of CNT, natural frequency decreases. Also results indicate that defect affect natural frequency of single walled carbon nanotubes.