CARBON NANOTUBES: NANOMACHINES AND SWITCHES

Deepak Srivastava
Computational Nanotechnology at NAS, NASA Ames Research Center, Moffett Field, CA 94035-1000

Carbon nanotubes and other fullerenes such as buckyball, carbon nanocones nanospirals and nanojunctions are expected to play a significant role in the design and operation of many nano-mechanical and nano-electronic devices of future. In this talk we will explore the role of carbon nanotubes in the formation of nanoscale gears, motors as well as electronic switches through classical and quantum molecular dynamics computer simulations. Carbon nanotube gears, formed by attaching benzyne rings on the body of a nanotube, are found to be stable under forced dynamic rotation with about 100GHz frequency. We show that it is possible to power these gears with external laser source to operate a nanomotor at about the same frequency. For a fixed laser field strength each carbon nanotube motor has an intrinsic frequency. We show that when the laser frequency is tuned close to the intrinsic frequency, stable unidirectional rotations of the gear motor with both cw and pulsed laser fields are possible. The performance with a pulsed laser field is better as compared to a cw laser field, because frictional heat generated in the former case is much less than the heat generated in the later. The role of carbon nanotubes in molecular electronic switching and computing devices is explored through quantum mechanical tight-binding molecular dynamics simulations. The electronic switching and computing devices are simulated by constructing 2- to 4-point carbon nanotube-heterojunctions where each branch of the junction has different electronic properties. The conceptual construction of a molecular network, made entirely of carbon, will be presented where each branch or node could be thought of as a molecular electronic component.