Electronic properties of silicon nanotubes with distinct bond lengths

We analyze the band structure of a silicon nanotube with sp³ bonds and variable bond lengths. This nanotube has many similarities with a carbon nanotube including a band gap at half-filling and conducting behavior which is dependent on structure. We derive a simple formula which predicts when the nanotube is metallic. We discuss our results in the context of a nanotube subject to small applied strains as this provides a means of distorting bond lengths in a predictable way and may be tested experimentally. The effects of strain on nanotube conductance have important implications for sensor technology.