STATIC POLARIZABILITIES OF SINGLE-WALL CARBON NANOTUBES

The static electric polarizability tenser of single-wall carbon nanotu bes is calculated within the random-phase approximation using a simple tight-binding model and a classical correction to include local field s. We find that the polarizability for constant fields parallel to the cylindrical axis is highly dependent on the details of the tube's ele ctronic structure. In contrast, the polarizability for fields perpendi cular to the axis only depends on the tube radius. The relative magnit udes of these two quantities suggests that under the application of a randomly oriented electric held, nanotubes acquire dipole moments poin ting mainly along their axes, with the size of the dipole inversely pr oportional to the square of the minimum direct band gap.