Effect of Finite Length on the Band gap of Semiconducting and Metallic Carbon Nanotube

In this work, density functional theory is used to study the effect of finite length on electronic property of different types of Single Walled Carbon Nanotubes (CNT). The change in band gap due to short length effect in case of metallic (5,2) CNT and semiconducting (4,5) CNT is discussed here. Ordinarily electrons are restricted along the circumference of carbon nanotubes. But in this investigation a supplementary restraint of electrons has been applied along the axis of tube by making the tube lengths short. Due to this short length effect, band gap value of both types of CNT reduces as length of the tube increases. But this change is not tedious. Rather it exhibits observable oscillations in short length. These oscillations have been interpreted with reference to the bonding characteristics of frontier orbitals. This investigation providing novel acumen into the large band gap opening of chiral CNTs could be valuable in advancing future applications of CNTs in optical, electronic devices.