Order–disorder phase transitions in a honeycomb lattice gas with first nearest neighbor exclusion: comparison between different approximations and a Monte Carlo simulation

The combinatorial factor method for investigation of surface adsorption

“…Thus, we can deduce that in surface adsorption there is a phase transition which can be predicted by this method. This finding is in agreement with the experimental and theoretical results [51][52][53]. However, we must note that this phase transition can be classified neither as the first-nor as the second-order.…”

“…The progress in this field has gained a particular impetus due to the introduction of several powerful experimental techniques (e.g., neutron scattering [25][26][27][28][29], various forms of electron spectroscopy [30][31][32][33][34][35][36][37][38][39], light particle, e.g. helium, scattering [3,40,41]), the extensive use of computer simulation methods (Monte Carlo and molecular dynamics [5,[42][43][44][45][46][47][48]) and, last but surely not least, owing to very intensive theoretical studies [20][21][22][49][50][51][52][53], whereby the discovery of rich two-dimensional world of phase transitions and substrate induced forms of order in adsorbed layers has become a challenge. At the same time, this has created a unique opportunity to verify various ideas and predictions stemming out of theoretical work.…”

Adsorption of gases on SnS2: trace of order–disorder phase transition of a honeycomb lattice gas

“…If disordered arrangement of atoms/molecules changes to ordered one as the adsorbed density increases, the packing of atoms/molecules in the lattice may become efficient and the increasing rate of the density with the equilibrium pressure will increase to bend the adsorption isotherm. Therefore the observed bending of the adsorption isotherms may be related to the O-DO phase transition of second order taking place in the gas adsorbed on the honeycomb lattice of sites of SnS 2 , if fcc and hcp sites have almost the same adsorption potential [1,2]. In the below, we try to explain our experimental findings from this standpoint in the framework of the quasi-chemical (QC) approximation.…”

“…We briefly review the previous QC theory [2] with addition of some modifications. The honeycomb lattice is divided into two (1 · 1)-1/2 sublattices, A and B.…”

“…If the two types of sites are equivalent with respect to the adsorption potential, these adsorption systems can be modeled with a honeycomb lattice gas with first n. n. exclusion. Our previous papers [1,2] have shown that such a lattice gas undergoes order-disorder (O-DO) 0039 phase transition of second order and that the first order phase transition also occurs at temperatures lower than the resultant tricritical point when atoms attract each other at second n. n. and farther sites. The order signifies the arrangement of atoms in long-range (1 · 1)-1/2 translational order.…”