Interfacial separation between elastic solids with randomly rough   surfaces: comparison between theory and numerical techniques
  We study the distribution of interfacial separations P(u) at the contact region between two elastic solids with randomly rough surfaces. An analytical expression is derived for P(u) using Persson's theory of contact mechanics, and is compared to numerical solutions obtained using (a) a half-space method based on the Boussinesq equation, (b) a Green's function molecular dynamics technique and (c) smart-block classical molecular dynamics. Overall, we find good agreement between all the different approaches. 
A. Almqvist, C. Campana, N. Prodanov and B.N.J. Persson
cond-mat.soft