Single-Walled Carbon Nanotubes: Geometries, Electronic Properties, and Actuation
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Carbon nanotubes were discovered in 1991 by means of transmission electron microscopy in the multiwalled form that consists of concentric shells of seamless cylinders of graphene (a layer of graphite). The quasi one-dimensional structure, large mechanical strength, and the conjugated electronic structure are among the most commonly mentioned properties of carbon nanotubes. Current and potential applications of carbon nanotubes include the probing tip in scanning tunneling microscopy, artificial “muscle”, units of electronic memory storage, to name just a few. The fascinating properties and potential uses have attracted much research interest in the carbon nanotubes.
The geometries, electronic properties and actuation of single-walled carbon nanotubes (SWNTs) obtained from high-level quantum mechanical calculations are presented in this entry. The commonly used quantum mechanical methods are first reviewed, then the behaviors of small to medium SWNTs with different structures are discussed and comparison with experimental results is made when possible. The behaviors of different groups of SWNTs are attributed to their electronic band structures.