Molecular dynamics (MD) simulations of the dependence of C–C bond lengths and bond angles on the tensile strain in single-wall carbon nanotubes (SWCNT)

Molecular dynamics (MD) simulations of tensile pulling of carbon nanotubes (SWCNTs) (both armchair and zigzag configurations) were conducted using the Brenner potential to investigate the variation of the six carbon–carbon bond lengths and bond angles of the hexagons in single-walled carbon nanotubes (SWCNT) as a function of tensile strain. The correlations between stress–strain, bond lengths and bond angles with strain, and the variation of a parameter in the interaction potential, namely, Dmin have been studied. Simulations at higher values of strain were also performed to obtain the values of breaking strain. A sharp change in the stress–strain behavior, C–C bond lengths, and bond angles with strain was observed for strains equals to 0.30 for the armchair and 0.18 for the zigzag SWCNTs. The dependence of bond stretching and breaking strain on the chirality of the nanotubes and the functional form of the empirical potential has been investigated. The results of our investigations suggest that the presence of attenuation functions in empirical potentials may cause problems, if bond distances or strains become larger than the onset point of these functions. The effect of the duration of relaxing/thermostating of the nanotube after every stretch on the value of the breaking strain has also been discussed.