Electronic and mechanical properties of sub-nm diameter carbon nanotubes

The electronic and mechanical properties of carbon nanotubes such as high Young's modulus and strength, high surface to volume ratio, and high electrical conductivity make them ideal for a wide range of uses from biomedicine to electronic devices. These properties are known to be diameter-dependent, but the diameter-dependency at sub-nanometer diameters and the mechanistic basis for the dependency is less well understood. In our work, using density function theory (DFT) simulations, we find that carbon nanotubes have two distinct bond lengths, with the nonuniformity in bond length being significant for sub-nm diameter nanotubes and affecting their properties. In this poster, we present the effects for both defective and non defective zigzag carbon nanotubes. We discuss the diameter dependent band gap and the electronic basis of the anomaly in theoretical predictions of bandgap size for (m,0) chirality nanotubes for m<7. We also present the diameter-dependence of Young's modulus, strength, and toughness for sub-nm diameter carbon nanotubes. For carbon nanotubes with monovacancy defect, we find that Jahn-Teller reconstruction does not occur due to high curvature of the nanotube, which is different from graphene. The electronic consequence for these findings will also be discussed.