This study investigates the thermodynamic properties of carbon monoxide (CO) adsorption on the Pt(100) surface using grand canonical Monte Carlo simulations of a two-dimensional square Ising model. Using finite-size scaling analysis for system sizes N = 10 − 50, we determine the pseudocritical temperature of the order–disorder transition to be T C 2.2856(7) (in units of |J|/k B ), in good agreement with Onsager’s exact solution. Subsequently, a lattice of size 50×50 with nearestneighbor repulsive interactions (J < 0) is employed to simulate adsorption isotherms and isobars and to characterize the phase behavior of the adlayer. The simulations successfully reproduce the formation of the ordered c(2×2) phase at half-coverage (θ = 0.5) in the low-temperature regime. Furthermore, the isosteric heat of adsorption, extracted from the simulated isotherms, exhibits a characteristic steplike decrease near the critical coverage, directly reflecting the effect of lateral repulsive interactions. These results provide a consistent microscopic description of the thermodynamic properties and phase behavior of the CO/Pt(100) system.
Phạm et al. (Fri,) studied this question.