Surface order-disorder phase transitions and percolation

M. C. GIMÉNEZ; A. J. RAMIREZ-PASTOR; F. NIETO

Génova, Italia.

Congreso; Statphys 2007 (International Conference on Statistical Physics); 2007

In the present contribution, the connection between surface order-disorder phase transitions and the percolating properties of the adsorbed phase has been studied. For this purpose, four lattice-gas models in presence of repulsive interactions have been considered. Namely, monomers on honeycomb, square and triangular lattices, and dimers (particles occupying two adjacent adsorption sites) on square substrates. By using Monte Carlo simulation and finite-size scaling analysis, we obtain the percolation threshold of the adlayer, c, which presents an interesting dependence with w/kBT (being w, kB and T, the lateral interaction energy, the Boltzmann’s constant and temperature, respectively). For each geometry and adsorbate size, a phase diagram separating a percolating and a non-percolating region is determined. From this analysis, a critical curve in the -T space was addressed. The line separating the percolating and non-percolating regions was explained in terms of simple considerations related to the interactions present in the problem.   Keywords: Percolation; Phase transitions; Monte Carlo simulation; Lattice-gas models