Ab Initio Study of Carbon Nanotubes in Electric Fields

Abstract

Electronic structures of four types of carbon nanotubes in an electric field have been investigated by the ab initio pseudopotential plane wave method. The local field enhancement at the tips of nanotubes and the screening of the electric field inside the nanotubes are considerable for nanotubes with a small gap between the highest occupied band (HOB) and the lowest unoccupied band (LUB) in the electronic states. The dangling bond (DB) states near the HOB localized at the edge of nanotubes are significantly influenced by the electric field. Thus, the present results strongly suggest an important role of the localized states of conducting nanotubes with small electronic gaps in field emissions.