Pentaheptite Allotropes of Carbon Nanotubes

Stone-Wales bond rotation converts 4 adjacent graphene hexagons into 2 pentagon-heptagone pairs. If such an algorithm is applied on all primitive cells of hexagons, graphene is transformed into a sheet of interlinked pentagones and heptagones. Under condition that pentagons occur only as isolated pairs 2D hexagonal and rectangular pentaheptite (57) lattices are obtained. We determine the symmetry of nanotubes (NTs) rolled up from these lattices and perform symmetry preserving relaxation in order to assess stability and conducting properties of 57NTs . Density functional tight binding calculations are carried out by full-symmetry implemented POLSym code. Vast majority of 57NT is found to be metallic having considerably higher electronic density of states at Fermi level than their metallic conventional counterparts. Pathway for synthesis of certain types of 57NTs directly from the conventional CNTs by putting them under uniaxial tension is p roposed. Release of the strain goes through formation of double pentagon-heptagone pairs.