A tight-binding model of a carbon nanotube interacting with TiO2 rutile (110) surface

Abstract

The electronic and the spatial structure of an armchair carbon nanotube (CNT) deposited on a (110) surface of titanium dioxide (rutile) is studied with a help of the density functional theory (DFT) and using a tight binding model. It is shown that an electrostatic potential due to an ionic surface of the rutile crystal may induce an energy gap at the Fermi level in the electronic structure of the nominally metallic CNT. The gap may reach a magnitude 0.02 eV depending on a symmetry of an arrangement of the CNT at the surface. The electron site occupations obtained from the DFT computations are used to deduce an analytic form of the external potential applied in the model. It is shown that the potential induces a substantial lattice distortion which contributes to an enhancement of the energy gap. The electronic structure obtained from the calculation based on the model is in a good quantitative agreement with the DFT results.