Magnetic response of single-walled carbon nanotubes induced by an external magnetic field.

Using first-principles density functional calculations, magnetically induced currents are obtained for zigzag single-walled carbon nanotubes. Clear differences and trends in current flow are observed between the different nanotube families. In particular, for a magnetic field applied along the tube axis, the current response of the λ = 0 infinite nanotubes is paramagnetic, whereas for λ = 1 and 2 nanotubes, the response is diamagnetic. The results are used to predict and interpret the significant changes in NMR properties for small molecules encapsulated inside a tube.