Smallest nanotube:: Breaking the symmetry of sp3 bonds in tubular geometries -: art. no. 125502

We describe how sp(2) carbon, threefold coordinated by other carbons, can be replaced by sp(3) carbon, also threefold carbon coordinated, to produce extremely small-diameter (similar to0.4 nm) carbon nanowires with only minimal bond-angle distortion. Under a naming convention analogous to that for ordinary carbon nanotubes, the smallest sp(3) tubes have wrapping indices (3, 0) and (2, 2). These systems have large band gaps and a stiffness larger even than that of traditional sp(2)-bonded carbon nanotubes. They therefore form the stiffest one-dimensional systems known.