Overdamped van Hove function of atomic liquids
  Using the generalized Langevin equation formalism and the process of contraction of the description we derive a general memory function equation for the thermal fluctuations of the local density of a simple atomic liquid. From the analysis of the long-time limit of this equation, a striking equivalence is suggested between the long-time dynamics of the atomic liquid and the dynamics of the corresponding \emph{Brownian} liquid. This dynamic equivalence is confirmed here by comparing molecular and Brownian dynamics simulations of the self-intermediate scattering function and the long-time self-diffusion coefficient for the hard-sphere liquid. 
Leticia L\'opez-Flores, Laura L. Yeomans-Reyna, Mart\'in   Ch\'avez-P\'aez and Magdaleno Medina-Noyola
cond-mat.soft