Monte Carlo study of multicomponent adsorption on triangular lattices

The adsorption process of interacting binary gas mixtures containing particles A and B on triangular substrates is studied through grand canonical Monte Carlo simulation in the framework of the lattice-gas model. The energies involved in the adsorption process are four: (1) epsilon(0), interaction energy between a monomer (type A or B) and a lattice site; (2) W-AA, nearest-neighbor interaction energy between two A particles; (3) W-AB (=W-BA), nearest-neighbor interaction energy between an A particle and a B particle and (4) W-BB, nearest-neighbor interaction energy between two B particles. The process is monitored through partial and total isotherms, differential heats of adsorption and energy of the system, which appear as very sensitive to all lateral interactions. We focus on the case of repulsive lateral interactions, where a rich variety of structural orderings are observed in the adlayer, depending on the value of the parameters W-AA, W-AB and W-BB. Results are rationalized through the determination of the phase diagrams characterizing second order phase transitions in the system. A nontrivial interdependence between the partial surface coverage of both species is observed. (C) 2008 Elsevier B.V. All rights reserved.