Theoretical Study of Axial Strain Effects on Aromaticity Factor in Single-Walled Zigzag Boron Nitride Nanotubes

In this study, the effects of the aromaticity on electronic properties of single-walled Boron Nitride Nanotubes (BNNTs) have been studied along with tension. The geometries were optimized at the B3LYP/6-31+G(d) level. In the axial tensile process, the B and the N atoms within two atomic layers at both ends of BNNTs were kept fixed, whereas the remaining layers were relaxed during the calculations. The values of the bandgap, binding energies, electronic chemical potential, chemical hardness, and electrophilicity index have been calculated. The Nucleus-Independent Chemical Shielding (NICS), Harmonic Oscillator Model of Aromaticity (HOMA), Harmonic Oscillator Model of Electron Delocalization (HOMED) and Para-Delocalization Index (PDI) have been calculated to quantify aromaticity in terms magnetic, structural and topological criteria. Our results indicate that the HOMED index is appropriate for determining the aromaticity of single-walled zig-zag BN nanotubes. Also, the aromaticity of these nanotubes decreases with the increase of axial strain. A reverse correlation is observed between aromaticity and conductivity of nanotubes along tension.