The growth energetics of carbon nanotubes during arc discharge conditions are investigated. Ab initio molecular dynamics calcualtions show that the electric field alone cannot stabilize the growth of open metallic tubes. The addition of atoms and small clusters to tubes were studied using realistic atomic potentials. Deposition on tubes narrower than Å3 nm leads to nucleation of curved defects (adjacent pentagon pairs) and eventual tube closure, while deposition on wider tubes favors the formation of hexagons and isolated pentagons, thereby promoting open-ended growth.

• Received 27 May 1994

DOI:https://doi.org/10.1103/PhysRevLett.73.2468