Growth of carbon nanotubes: a molecular dynamics study

Molecular dynamics with realistic many-body atomic potentials was used to study the growth of carbon nanotubes. Analysis of the bond switching and ring migration processes has led to an identification of tube growth mechanisms. Wide tubes, initially open, were found to grow straight maintaining an all-hexagonal structure, while narrow tubes were found to develop permanent pentagonal rings that lead to tube closure upon further deposition. Continued deposition on the top of a closed tube yields a disordered cap structure, implying that open tubes are critical for defect-free growth.