Two configurations of perfect single walled carbon nanotubes (armchair and zigzag) were simulated based on the finite element method. Then, three most likely defects (Si-doping, carbon vacancy and perturbation) were introduced to the models to represent defective forms of single walled carbon nanotubes (SWCNTs). Finally, the vibrational properties of perfect and defective carbon nanotubes were evaluated and compared. The results showed that SWCNTs have a natural frequency with a rather high value between 18.69 and 24.01 GHz. In the consideration of the natural frequency of the defective SWCNTs, it was also observed that the existence of any type of defects or irregularities leads to a lower value of natural frequency and vibrational stability. Simple mathematical relations which express the change in natural frequency versus the percentage of the defect were also presented. This can be very useful to realistically estimate the influence of defects of different amounts on the vibrational behavior of carbon nanotubes.
Structural and Vibrational Properties of C60 and C70 Fullerenes Encapsulating Carbon Nanotubes
