Pentaheptide alotropes of carbon nanotubes

Abstract

Stone-Wales bond rotation transforms four adjacent graphene hexagons into a pentaheptide ornament consisting of two pentagons and two heptagons. There are two types of lattices of these ornaments, one hexagonal and the other one rectangular. We determine symmetry of arbitrary rolled up nano tubes of both types. This is used to relax the purely folded configurations for large number of tubes, and compare thei stability and electronic properties to the properties of the generic graphene single-wall nanotubes. Density functional tight binding calculations are performed by the full-symmetry implemented numerical code POLSym. Generally, pentaheptide tubes are less stable than the generic ones, and vast majority of them is conducting. For the particular tubes we predict transition from generic to the pentaheptide form by applying mechanical stress. © 2007 American Institute of Physics.