Dynamics of adparticles far from equilibrium conditions

The collective diffusion coefficient is studied for a system of particles adsorbed on a surface with two non-equivalent adsorption sites. The non-equilibrium conditions are characterized by the non-equilibrium distribution of atoms between adsorption sites with different energy of adsorption. The determination of the diffusion coefficient is based on the general theory published in [J. Phys. Condens. Matter. 12 (2000) 6343] and links to the former studies of the diffusion coefficient and phase diagrams of the same systems in equilibrium. Our analysis shows that non-equilibrium conditions strongly influence the step-like dependence of diffusion coefficient on coverage, as determined in equilibrium conditions for non-interactive adparticles, and that the diffusion coefficient can even have an opposite behavior. Far from equilibrium the appearance of a local maximum is observed. These deviations reflect the influence of the state of the adparticle system on their collective behavior.