DFT study of NH3 adsorption on the (5,0), (8,0), (5,5) and (6,6) single-walled carbon nanotubes. Calculated binding energies, NMR and NQR parameters

Behavior of a single NH3 molecule adsorbed on external surface of H-capped (5,5), (6,6), (5,0), and (8,0) single-walled carbon nanotubes (SWCNTs) is studied via DFT calculations. Binding energies clearly exhibit adsorption dependence on tube diameter. 13C, 15N and 1H chemical shielding tensors are calculated at the B3LYP level using GIAO method. NMR calculations reveal that 13C chemical shielding of (8,0) is more sensitive to NH3 adsorption compared to (5,5), (6,6) and (5,0) tubes. 15N and 1H chemical shielding correlate noticeably with diameter of the nanotubes. 14N and 2H nuclear quadrupole coupling constants, CQ, and asymmetry parameter, η, reveal the remarkable effect of NH3 adsorption on electronic structure of the SWCNTs.