Fig. 4

Sample spectra obtained for graphene from parameterized force-field molecular dynamics at 50 K and the velocity auto-correlation method. The E_2g symmetry modes are isolated at the Γ-point by projections. All spectra are calculated using 50,001 configurations. a REBO⁶⁰, b AIREBO-M⁶¹, c LCBOP⁶², and d Tersoff⁶³. Together, the deviation of the spectral lineshapes from that of the corresponding AIMD result (Fig. 3d) and the inability of the analytical model to fit the data suggest that the potentials create inaccurate trajectories for oscillations close to equilibrium