Young's moduli of carbon materials investigated by various classical molecular dynamics schemes

F Gayk and J Ehrens and T Heitmann and P Vorndamme and A Mrugalla and J Schnack, PHYSICA E-LOW-DIMENSIONAL SYSTEMS & NANOSTRUCTURES, 99, 215-219 (2018).

DOI: 10.1016/j.physe.2018.02.009

For many applications classical carbon potentials together with classical molecular dynamics are employed to calculate structures and physical properties of such carbon-based materials where quantum mechanical methods fail either due to the excessive size, irregular structure or long-time dynamics. Although such potentials, as for instance implemented in LAMMPS, yield reasonably accurate bond lengths and angles for several carbon materials such as graphene, it is not clear how accurate they are in terms of mechanical properties such as for instance Young's moduli. We performed large-scale classical molecular dynamics investigations of three carbon-based materials using the various potentials implemented in LAMMPS as well as the EDIP potential of Marks. We show how the Young's moduli vary with classical potentials and compare to experimental results. Since classical descriptions of carbon are bound to be approximations it is not astonishing that different realizations yield differing results. One should therefore carefully check for which observables a certain potential is suited. Our aim is to contribute to such a clarification.

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