Endohedral carbon chains in chiral single-wall carbon nanotubes

Using a first-principles, local density functional approach, we report the bond length optimization of endohedral linear carbon chains. In these calculations, all-carbon nanowire structures were constructed by inserting cumulenic linear carbon chains inside the semiconducting (7,3) and metallic (7,4) single-wall carbon nanotubes with radii of similar to 0.35 nm. Our calculations show that the total energy results for the enclohedral chains inside both (7,3) and (7,4) nanotubes are well described with a common total energy curve having an equilibrium bond length of similar to 0.129 nm. The electronic band structures of the carbon nanowires are described in terms of a rigid-band model, with the Fermi level for the carbon nanowire effectively pinned near the top of bands originating from the valence band of the single-wall nanotube. (C) 2006 Wiley Periodicals, Inc.