Critical behavior of repulsive linear k-mers on triangular lattices

P.M. PASINETTI; F. ROMÁ; J. L. RICCARDO; A.J. RAMIREZ PASTOR

PHYSICAL REVIEW B - CONDENSED MATTER AND MATERIALS PHYSICS

American Physical Society

Año: 2006 p. 155418 - 155425

0163-1829

Monte Carlo MC simulations and finite-size scaling analysis have been carried out to study the critical behavior in a submonolayer two-dimensional gas of repulsive linear k-mers on a triangular lattice at coverage k/2k+1. A low-temperature ordered phase, characterized by a repetition of alternating files of adsorbed k-mers separated by k+1 adjacent empty sites, is separated from the disordered state by an order-disorder phase transition occurring at a finite critical temperature, Tc. The MC technique was combined with the recently reported free-energy minimization criterion approach FEMCA F. Romá et al., Phys. Rev. B 68, 205407 2003 to predict the dependence of the critical temperature of the order-disorder transformation. The dependence on k of the transition temperature, Tck, observed in MC is in qualitative agreement with FEMCA.In addition, an accurate determination of the critical exponents has been obtained for adsorbate sizes ranging between k=1 and 3. For k1, the results reveal that the system does not belong to the universality class of the two-dimensional Potts model with q=3 k=1, monomers. Based on symmetry concepts, we suggested that the behavior observed for k=1, 2, and 3 could be generalized to include larger particle sizes k2.