Atomistic nucleation and growth mechanism for single-wall carbon nanotubes on catalytic nanoparticle surfaces.

We demonstrate an atomistic nucleation and growth mechanism for single-wall carbon nanotubes (SWNTs) on catalytic nanoparticle surfaces based on a core-shell model. We show by ab initio calculations that strain relief between the metal core and carbon shell plays a crucial role in facilitating the hexagonal tubular growth. The incipient nucleation begins with the formation of a hemispherical fullerene cap by a size-selected core-shell bonding process which is followed by a repeated phase-separating growth mode with increasing energetic stability via periodic pulsatile strain relief along the tubular growth pathway. These results provide an excellent account for experimental observations and shed new light on the origin and underlying dynamics of SWNT growth.