Based upon (6,0) zig-zag carbon nanotubes, a Stone-Wales defect ring ([5.7]3) was constructed at one end of the zig-zag carbon nanotubes, forming a novel nanostructure [5.7]3 zig-zag carbon nanotube. The introduction of [5.7]3 breaks the centrosymmetry of the nanotube and markedly changed the electronic and magnetic properties of the nanotube. Unlike the (6,0) zig-zag carbon nanotubes which had an open-shell singlet ground state, the [5.7]3 zig-zag carbon nanotubes had a closed-shell singlet ground state with a large dipole moment, polarizability, and first hyperpolarizability. Interestingly, the [5.7]3 zig-zag carbon nanotubes itself had a donor-π-acceptor framework, in which the Stone-Wales defect ring serves as an electron donor while the zig-zag nanotube works as an electron acceptor and a conjugated bridge. Moreover, increasing both the tube diameter and tube length could enhance second-order non-linear optical responses, with the former being more effective than the latter.

Theoretical Investigation on Nonlinear Optical Properties of Carbon Nanotubes with Stone-Wales Defect Rings. Z.J.Zhou, G.T.Yu, F.Ma, X.R.Huang, Z.J.Wu, Z.R.Li: Journal of Materials Chemistry C, 2014, 2[2], 306-11