Single-walled carbon nanotube growth from a cap fragment on an iron nanoparticle: Density-functional tight-binding molecular dynamics simulations

Growth of a single-walled carbon nanotube (SWNT) from a corannulene cap fragment on an iron cluster is demonstrated using density-functional tight-binding molecular dynamics simulations of laser synthesis. In order to explore multiple reaction pathways for the cap fragment to evolve into tubular form on the iron surface, reaction dynamics between the metal-bound cap fragment and gas-phase carbon atoms were investigated. It is found that rapid growth of the cap fragment can take place when carbon atoms are supplied in the vicinity of the cap fragment. In this reaction process, a high-density supply of add atoms leads also to rearrangements of existing s p2 -carbon-cap structures involving the formation of pentagons and heptagons as long-lived defects, while short-lived four- and eight-membered rings and short polyyne chains appear during the dynamics as important intermediate structures, facilitating growth.