Density Functional Theory Study on the Static Dipole Polarizability of Boron Nitride Nanotubes: Single Wall and Coaxial Systems

Optical and electronic properties are evaluated for infinite periodic boron nitride nanotubes (BNNTs) within density functional theory framework. Specifically, the static dipole polarizability and the band gap of the single-walled zigzag and armchair tubes as well as the double-walled zigzag nanotubes are calculated. Four density functional methods of different categories, namely, PBE, TPSS, VSXC, and HSE have been considered for our purpose. Our results allow promising application of the HSE functional in predicting band gap of infinite periodic nanotubes and similar compounds. The behaviors of DFT methods we obtained for single-walled boron nitride nanotubes are also preserved for predicting the band gap and shielding efficiency of double-walled BNNTs. In double-walled coaxial tubes, the interwall interaction is found to reduce the band gap distinctly and to have only minor effects on the polarizabilities of constituent tubes. In contrast with multiwalled carbon nanotubes, where the inner tube is almost completely shielded by the outer tube, in the studied double-walled BNNTs the inner tube is only partially shielded by the outer shell. This study has implication for nanoelectronics and specifically suggests a new route to efficiently design novel nanodevices with tunable gaps.