Abstract:
We have performed optimization of (5,0) zigzag and (5,5) armchair single-walled carbon nanotube and SiC nanotube using density functional theory at zero spin and high spin values. Further, Infrared and Raman spectra, highest occupied and lowest unoccupied molecular orbitals and their gap and natural bond orbital analysis were carried out at optimized structures of these materials. Three different exchange and correlation functionals PBE, LSDA and HCTH along with cc-pVDZ basis set were used. For conspicuous normal modes assignments of both the (5,0) zigzag and (5,5) armchair single-walled carbon nanotube and SiC nanotube, potential energy distributions of the normal modes were calculated using normal coordinate analysis. The diameter of carbon nanotube and SiC nanotube in (5,0) zigzag form were optimized at 4.0 ?, and 5.0 ?, respectively and in (5,5) armchair form were optimized at 7.0 ?, and 8.0 ?, respectively at all the three level of theories.