Nonlinear diffusion coefficients in nonideal adsorbate layer on monocrystal surface

Nonlinear dependences of diffusion matrix elements on densities of monocrystal surface coverage in multicomponent adsorbate layer are defined. These dependences are shown to have discontinuities and regions with vanishing values. Discontinuities are connected with phase transformations of order-disorder type, that result in forming of two-dimensional crystals with different symmetry in the adsorbate layer (super-structures). The regions of vanishing diffusion coefficients correspond to two-dimensional two-phase states of gas-liquid, gascrystal and liquid-crystal types.