The electronic properties of carbon nanotubes CNTs, such as ionization potential (IP), electron affinity (EA), energy gap (Eg), Fermi energy (Ef), binding energy (Eb), the density of state (DOS), and IR spectral properties, investigated after substituted the OH, SO, SiO2, H2O, and N2 groups on the optimization structure of CNT (3,3). The lengths of C=C for zigzag CNT (3,3) slight altered with substituted the mention groups and given the depress in bond length during the substituted – OH, -SO, and –SiO2 that attitude to bond orders for these substituted groups and different in electronegativitypowerforanoxygenatominthesegroups.Moreover,theC-CbondforzigzagCNT(3,3)changedalso, and gave a slight increase during the substituted OH group, but decreased during substituted So and SiO2 groups. The substituted of – SO and –SiO2 on the structure of CNT (3,3) demonstrated, fewer values of total energies that will increase the stability of CNT. The CNTS-SiO2 has a less value for bandgap compared with other substituted materials, this behaver has given it a good electronic conductivity. The B3LYP functional theory has been used to conduct the DFT approach. The analyzed Nano species agree well with the experimental results based on the measured values of HOMO and LUMO energies.

Electronic Structure, Band Gap, CNTs, B3LYP Functional Theory, HOMO and LUMO Energies