Threshold displacement energies in graphene and single-walled carbon nanotubes

A Merrill and CD Cress and JE Rossi and ND Cox and BJ Landi, PHYSICAL REVIEW B, 92, 075404 (2015).

DOI: 10.1103/PhysRevB.92.075404

The threshold displacement energy E-d has been determined for graphene and 216 different (n, m) single-walled carbon nanotube chiralities, with 5 <= n <= 20 and 0 <= m <= n, under several model conditions using classical molecular dynamics. The model conditions vary by particle (electron or carbon ion), empirical potential (two parametrizations of Tersoff J. Tersoff, Phys. Rev. B 39, 5566 (1989); L. Lindsay and D. A. Broido, 81, 205441 (2010) and one of Brenner et al. D. W. Brenner, O. A. Shenderova, J. A. Harrison, S. J. Stuart, B. Ni, and S. B. Sinnott, J. Phys.: Condens. Matter 14, 783 (2002)), and momentum transfer direction (towards or away from the nanotube axis). For electron irradiation simulations, E-d exhibits a smoothly varying chirality dependence and a characteristic curvature influenced by the momentum transfer direction. Changing the empirical potential shifts the magnitude of E-d, but the trend is preserved for electron simulations. However, the perturbation in the knock-on dynamics introduced by the carbon ion leads to E-d trends that diverge from the equivalent electron simulation. Thus, the ion interaction has a non-negligible effect on the dynamics of the collision and leads to E-d values that can distinctly vary depending on the selected carbon nanostructure.

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