M painshahri - Department of Chemistry, Shahre Rey Branch, Islamic Azad University, Tehran,Iran
M Noei - Department of Chemistry, Mahshahr Branch, Islamic Azad University, Mahshahr, Iran

The electronic structures and Nuclear magnetic resonance (NMR) parameters including isotropic and anisotropic chemical shielding parameters were calculated using density functional theory (DFT) for silicon or Germanium-doped carbon nanotubes. Geometry optimizations were carried out at the (BLYP,B3LYP/6-31G*) and (BLYP,B3LYP/6-31G**) level of theory using the Gaussian 03 program suite. We have also investigated the total electronic properties, HOMO, LUMO and energy gap for CNT with Si and Ge.The calculations indicated that doping of C atom by Si or Ge atom had a more significant influence on the calculated shielding tensors than did doping of the C atom by Si or Ge atom. In comparison with the pristine model, Si or Ge-doping of C sites of the zigzag nanotubes increases the energy gaps of the nanotubes and reduces their electrical conductance. These results are expected to give valuable information in building nanoscal electronic devices

Carbon nanotubes, NMR (Nuclear magnetic resonance), Chemical shielding , DFT (density functional theory)