DYNAMICS OF INTERACTING BROWNIAN PARTICLES IN A 2-DIMENSIONAL PERIODIC POTENTIAL

The static structure factor and diffusion mechanism of N interacting B rownian particles immersed in a two-dimensional periodic potential are discussed, in relation with superionic conductors, premelting surface s and adsorbed monolayers. For the static structure factor we report B rownian dynamics results assuming a repulsive Yukawa pair potential. F or some values of the concentration, the system can be decomposed in t wo equivalent or in two different subsystems along the two directions of space. To get information about the diffusion mechanism, we have co mputed the full width at half maximum (f.w.h.m.) Delta(q), of the quas i-elastic line of the dynamical structure factor S(q, omega) up to lar ge values of q covering several Brillouin zones. The entire analysis o f Delta(q) with different physical parameters shows that the most prob able diffusion process in good superionic conductors (concentration of mobile ions c=2/3) consists of a competition between a back correlate d hopping in one direction and forward correlated hopping in addition to liquid-like motions in the other spatial direction.:The analytical treatment of this investigation is done by using different approximati ons such as the homogeneous approximation and the time dependent mean field approximation within the lattice gas model.