III International Conference

PP-I-37ISOTHERMS FOR STEPPED SURFACES: MODELINGMyshlyavtsev A.V. 1, 2 , Myshlyavtseva M.D. 1 , Evsejeva S.I. 11 Omsk State Technical University, Omsk, Russia2 Institute of Hydrocarbons Processing SB RAS, Omsk, RussiaE-mail: myshl@omgtu.ruThe simple lattice gas model of stepped surfaces is considered. In the framework of thismodel there are the strong and weak adsorption centers and adsorbate – adsorbate lateralinteraction too. The transfer matrix method and Monte Carlo method have been applied tostudy this model. It was shown, the dependencies of the local coverage may benonmonotonuous functions of chemical potential.Heterogeneity is a common phenomenon for the most of real surfaces. The simple modelof stepped surfaces is considered. Our model is a lattice gas model on a square lattice. It isshown in Fig. 1. The width of terraces is noted as L (L ≥ 2). The adsorption sites belonging tothe each first (adsorption centers which are located near steps) and last row are assumed to bethe strong adsorption centers and the weak adsorption centers, respectively. The nearest –Fig. 1.chemical potential,Δ1 /Δ2neighbors adsorbate – adsorbate lateral interactions aretaken into account as well. These are independent of theadsorbed particles location. The thermodynamicHamiltonian for developed model can be written as∑∑∑∑H = ε ninj− μ ni− Δ1nk− Δ2nl, (1)< nn>iklwhere ε is the lateral interactions energy, μ thethe energy difference between the strong/weak adsorption centersand terrace centers (Δ1 >0,Δ nn2