Intrinsic dipole moment on the capped carbon nanotubes

Local atomic geometry and dimensionality of the nanoscale material consisting of carbon atoms with threefold coordination are crucial for determining their electronic properties. Due to the local electronic structure difference between the pentagonal and hexagonal C sites, the capped carbon nanotubes are found to possess an intrinsic dipole moment of 3.5 debye around their cap region. Our first-principle total-energy calculations clearly indicate that mixed dimensionality of the capped nanotube results in the charge transfer from the nanotube to the cap region. This is a mechanism of the electron polarization of materials. Furthermore the results corroborate the importance of the interplay between the electronic and geometric structures in nanoscale materials