The electronic properties of chiral carbon nanotubes

Abstract

Structural changes in carbon nanotubes (CNTs) alter electronic properties of these structures at the atomic scale. In this work, structure optimization and electronic property of infinitely long chiral CNTs are calculated using the first-principles density functional theory. The infinitely long chiral CNTs, namely, single-, double-, and triple-walled CNTs are obtained by imposing the periodic boundary conditions. Analysis of band structure showed that for chiral SWCNTs, a semiconductor is produced when n−m≠3q, whereas a conductor is produced when n−m=3q; For chiral DWCNTs we investigated, a semiconductor is produced when n1−m1≠3q @ n2−m2=3q, whereas a conductor is produced when n1−m1≠3q @ n2−m2≠3q (or n1−m1=3q @ n2−m2=3q); For chiral TWCNTs we investigated, a conductor is produced when n1−m1≠3q @ n2−m2≠3q @ n3−m3=3q (or n1−m1=3q @ n2−m2=3q @ n3−m3=3q). Energy gaps are caused by the curvature of the tube wall, and they are more remarkable as diameter decreases.