Study of surface temporal fluctuations by mean field lattice gas model

We examine the behaviour of the current correlation function of small surfa ces equivalent to the probe areas in the scanning tunnelling microscopy exp eriments with the interactions, the surfaces size and the coverage. The kin etics is described by the mean field master equation in the context of latt ice gas model. The results show that for both the non-interacting case and in presence of repulsive interactions susceptible to produce an order-disor der transition in the system, the correlation function varies as 1/D(c)t in the long time regime. We calculate the collective diffusion coefficient us ing the linear response theory as well as the correlation function method a nd we find a good agreement between both results except for the half full l attice. (C) 2001 Elsevier Science B.V. All rights reserved.