The influence of NH3-attaching on the NMR and NQR parameters in the (6,0) zigzag single-walled BPNTs: a density functional study

The structural properties, NMR and NQR parameters in the pristine and NH3-attached (6,0) zigzag BPNTs model were calculated using DFT methods in order to evaluate the influence of NH3-attached on the (6,0) zigzag BPNTs for the first time. Geometry optimizations were carried out at the BLYP, B3LYP/6-31G* levels of theory using the Gaussian 03 program suites. The chemical shielding (CS) parameters for the sites of various 11B and 31P atoms and quadrupole coupling constant (CQ), and asymmetry parameter (ηQ) at the sites of various 11B nuclei were calculated in the pristine and the NH3-attached (6,0) zigzag BPNTs model. The values of dipole moments detect notable changes due to direct effect of the NH3-attached on the BPNTs; however, the tip diameters are slightly significant changed in comparison to the pristine models and the gap energies of the NH3-attached BPNT do not detect any changes in comparison to the pristine model. For the NH3-attached BPNT, the NMR values for the 11B14 atom which is directly bonded to the NH3 molecule and the 31P atoms that directly bonded to the 11B14 atom in the BPNT are significantly changed. CSI parameters of the atoms are increased whereas CSA parameters of the atoms are decreased. The NQR results showed that in BPNTs, the B atoms at the edges of nanotubes play dominant roles in determining the electronic behaviors of BPNTs and the average value of CQ (11B) and ηQ for the NH3-attached (6,0) zigzag BPNTs is further in comparison to the pristine model.