Linear Optical Susceptibility of Single-Walled Boron Nitride Nanotubes

A simple model based on an effective-mass approximation is developed to describe the dispersion behavior of the linear optical susceptibility χ1 of an array of aligned, identical single-walled boron nitride nanotubes (BNNTs) in the spectral range where interband π-electron transitions dominate. An analytic closed-form expression for χ⁽¹⁾ valid in the low-frequency part of the spectrum is obtained in terms of the band gap Δ_g of BNNTs and the π-electron transfer integral V_ppπ. To the best of our knowledge, the present analytic calculation is the first for such nanotubes.