  The electrical properties of a carbon nanotube depend strongly on its lattice
structure as defined by chiral and translational vectors. A toroidal shape for
a nanotube allows various twisted structures to exist along the direction of
the tube axis. We theoretically investigate the kinematics of conducting
electrons and persistent currents in toroidal carbon nanotubes. We show that
persistent currents exhibit a special characteristic of the cylindrical lattice
structure in twisted cases. We discuss the possibilities that the twist alters
the period of the current to one half the flux quantum and that the current
flows without an external magnetic field.
