Structural and electrical response of the (4, 0), (5, 0) and (6, 0) zigzag model of single-walled boron nitride nanotube (BNNT) with H-terminated at the open ended, have been investigated under the external electric field (EF) with intensities 0–1.6 × 10-2 a.u. using the DFT B3LYP/6-31G* level of theory. Results of this study show that with increasing BNNTs diameter, the HOMO-LUMO gap (HLG) values increase, and with increasing the EF intensity, the HLG values decrease. In both cases with increasing EF intensity and the BNNT diameters, the electric dipole moment is increased significantly. Also the calculated natural bond orbital (NBO) atomic charges on the atoms of the BNNT show that the separation of the center of the positive and the center of the negative electric charges of the boron nitride nanotubes are increases in both case. We have found that the properties of the BNNTs are dependent on their diameters and can be tuned by applied electric fields intensity.
