Ab initio investigations of the full static dielectric response and Born effective charge of BN nanotubes (BN-NTs) have been performed using finite electric-field method. It is found that the ionic contribution to the static dielectric response of BN-NTs is substantial and also that a pronounced chirality-dependent oscillation is superimposed on the otherwise linear relation between the longitudinal electric polarizability and the tube diameter $\left(D\right)$, as for a thin dielectric cylindrical shell. In contrast, the transverse dielectric response of the BN-NTs resembles the behavior of a thin (nonideal) conducting cylindrical shell of a diameter of $D+4\mathrm{\AA }$, with a screening factor of 2 for the inner electric field. The medium principal component $Z_y^{*}$ of the Born effective charge, corresponding to the transverse atomic displacement tangential to the BN-NT surface, has a pronounced $D$ dependence (but independent of chirality), while the large longitudinal component $Z_z^{*}$ exhibits a clear chirality dependence (but nearly $D$ independent), suggesting a powerful way to characterize the diameter and chirality of a BN-NT.

• Received 12 February 2007

DOI:https://doi.org/10.1103/PhysRevB.75.245403