Cluster variation theory of the condensation of atoms in a honeycomb lattice gas with first nearest neighbor exclusion

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

“…We consider the reason why the previous CVM theory [1] is not so accurate as expected. In the previous paper we investigated a special case in which the B-sublattice repels atoms with an infinitely high potential energy.…”

“…From this viewpoint, we have studied condensation of a honeycomb lattice gas in a previous paper [1]. The cluster variation method (CVM) [2][3][4][5][6] has been applied to hexagonal clusters overlapped at their sides.…”

“…In this paper we develop different approximations of lower class, i.e., Bragg-Williams (BW) and quasi-chemical (QC) approximations [13], for the same lattice gas model as treated in the previous paper [1]. In addition, we perform a Monte Carlo simulation [14].…”

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.…”

“…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.…”