  Structure and thermodynamics of crystalline membranes are characterized by
the long wavelength behavior of the normal-normal correlation function G(q). We
calculate G(q) by Monte Carlo and Molecular Dynamics simulations for a
quasi-harmonic model potential and for a realistic potential for graphene. To
access the long wavelength limit for finite-size systems (up to 40000 atoms) we
introduce a Monte Carlo sampling based on collective atomic moves (wave moves).
We find a power-law behaviour $G(q)\propto q^{-2+\eta}$ with the same exponent
$\eta \approx 0.85$ for both potentials. This finding supports, from the
microscopic side, the adequacy of the scaling theory of membranes in the
continuum medium approach, even for an extremely rigid material like graphene.
