Many-particle surface diffusion coefficients near first-order phase transitions at low temperatures

作者：Medved Igor^*; Trnik Anton

来源：Physical Review E, 2012, 86(1): 011601.

DOI：10.1103/PhysRevE.86.011601

We analyze the chemical and jump surface diffusion coefficients, D-c and D-J, near a first-order phase transition at which two phases coexist and the surface coverage,., jumps between single-phase values theta*(-) and theta*(+). Contrary to other studies, we consider temperatures that are sufficiently subcritical. Using the local equilibrium approximation, we obtain approximate analytical formulas for the dependences of D-c and D-J on the coverage and system size, N, near such a transition. In the two-phase regime, when. ranges between theta*(-) and theta*(+), the diffusion coefficients behave as the sums of two hyperbolas, D-c approximate to A(-)/N vertical bar theta - theta*(-)vertical bar + A(+)/ N vertical bar theta - theta*(+)vertical bar and D-J approximate to A(-)vertical bar theta - theta*(+)vertical bar/theta + A(+)vertical bar theta - theta*(-)vertical bar/theta. This behavior rapidly changes as the system goes from the two-phase regime to either of the single-phase regimes (when theta goes below theta*(-) or above theta*(+)). The crossover behavior of D-c(theta) and D-J (theta) between the two-phase and single- phase regimes is described by rather complex formulas involving the Lambert function. We consider a lattice-gas model on a triangular lattice to illustrate these general results, applying them to four specific examples of transitions exhibited by the model.

• 出版日期2012-7-10