The Relaxation Dynamics of a Supercooled Liquid Confined by Rough Walls

Abstract

We present the results of molecular dynamics computer simulations of a binary Lennard-Jones liquid confined between two parallel rough walls. These walls are realized by frozen amorphous configurations of the same liquid and therefore the structural properties of the confined fluid are identical to the ones of the bulk system. Hence, this setup allows us to study how the relaxation dynamics is affected by the pure effect of confinement, i.e., if structural changes are completely avoided. We find that the local relaxation dynamics is a strong function of z, the distance of the particles from the wall, and that close to the surface the typical relaxation times are orders of magnitude larger than the ones in the bulk. Because of the cooperative nature of the particle dynamics, the slow dynamics also affects the dynamics of the particles for large values of z. Using various empirical laws, we are able to parametrize accurately the z dependence of the generalized incoherent intermediate scattering function Fs(...