Energy Band Properties of the Chiral Carbon Nanotubes

The principal properties of electronic energy band structure for the chiral single-walled carbon nanotube (SWNTs) were investigated. Methods to decide the subband index crossing or approaching the Fermi level and decided the related wave vector ky are developed. Starting from the 　A-B effect, the conditions of metal-semiconductor transition continuously for the chiral SWNTs under inducing by the magnetic field are deduced and the general change pattern of energy gap is discussed in detail.