Sulfur doping at the tips of (6,0) boron nitride nanotube: A DFT study

We have investigated sulfur (S) doping at the tips of (6,0) boron nitride nanotube (BNNT) by density functional theory (DFT) calculations. Bond lengths, tubular diameters, dipole moments, band gaps, and quadrupole coupling constants (Cq) have been calculated in four models of the investigated BNNT: pristine, S-doping at the boron (B) tip, S-doping at the nitrogen (N) tip, and S-doping at both the tips. The results indicated the influence of the S-doping on the electronic and structural properties of the (6,0) BNNT. The B-N bond lengths do not differ in the S-doped models but the tubular diameters at S-doped tips are increased. The values of dipole moments and band gaps are reduced in the S-doped models. The Cq parameters revealed that the S-N bonds could be weaker than the B-N bonds whereas the B-S bonds could be stronger. We have also indicated that the properties of the S-doped models are independent of the dangling effects.