Atomistic growth model with edge diffusion for chiral carbon nanotubes

Abstract

We carried out exact finite-size analysis and numerical simulation within a kinetic 5-vertex model to study the growth dynamics of chiral carbon nanotubes. The model comprises carbon atoms deposition and migration at the nanotube edge considered as Markov processes and a generalized Glauber dynamics is assumed. The physical parameters considered are the supersaturation of the carbon fluid phase, the synthesis temperature and the nanotube chirality which is known to be fixed by the nucleated cap. In the model, we are interested by the elongation of the nucleus in a tube. We calculated the growth rate and edge defect densities . The growth modes of the tube have been singled out in the model parameters’ space. It has been found that spiral growth by pre-existing steps displacements is present beyond 1D-nucleation and continuous growth. In particular we obtained that in suitable physical conditions, the growth rate increases proportionally with the chiral angle θ of the nanotube up to a critical value θ c which depends on values of model parameters. • Mapping of a chiral SWCNT growth onto a kinetic 5-vertex model. • Deposition and diffusion of carbon atoms at the SWCNT edge are considered. • Exact calculations and Monte Carlo simulation methods are used. • Growth rates and defects densities are calculated and growth modes of the CNT edge specified. • The elongation rate and the SWCNT chirality are linearly correlated in some model parameters ranges.