Dependence of workfunction on the geometries of single-walled carbon nanotubes

Abstract

The effective workfunctions of single-walled carbon nanotubes of armchair(5,5) andzigzag (9,0) with various geometries have been calculated by first-principlescalculations. The results show that the capped and H-terminated zigzag(9,0) carbon nanotubes exhibit a lower workfunction value than the armchair(5,5) nanotubes with a similar diameter. The open-ended (without H termination)(5,5) nanotube, on the other hand, shows a lower workfunction than the open-ended(9,0) structure. The former exhibits a significant formation of triple bonds at its mouth partafter relaxation, which reduces the surface dipole and lowers its workfunction, the latterexhibits a higher density of unsaturated dangling bonds, raising its surface dipole andgiving a higher value of workfunction.