Singularities in the coverage dependence of the chemical diffusion coefficient, near to critical points which corresponded to transitions from one phase to another, were studied by using 2 different lattice-gas models. In the case of a hard hexagon model, the chemical diffusion coefficient was exactly equal to zero at the critical coverage. Its behavior near to this point was also in agreement with the predictions of scaling theory, provided that account was taken of Fisher renormalization of the specific heat exponent. In the case of a square lattice with repulsive interactions between nearest-neighbor particles, detailed transfer-matrix and Monte Carlo data indicated that the chemical diffusion coefficient went through a minimum at critical coverages. Its value at these points decreased with increasing lattice size.

A.V.Myshlyavtsev, A.A.Stepanov, C.Uebing, V.P.Zhdanov: Physical Review B, 1995, 52[8], 5977-84