Phase Transitions in Chemisorbed Layers on Crystal Surfaces

Abstract

Publisher Summary 2-Dimensianal discrete lattice models display a variety of phase diagrams and an interesting critical behavior at the points or lines of continuous phase transitions which due to the universality hypothesis provides full information about the critical behavior of a large class of two-dimensional systems. A lot of methods are developed for calculation of thermodynamic properties of discrete lattice models. The most often used ones are Monte Carlo calculations, low and high temperature series expansions and variational methods including mean field approximation. An attention should be paid to the regions in which phase transitions occur. There the finite size or finite cluster methods fail to reproduce the right critical behaviour. In this case the renormalization group (RG) method, especially the real space renormalization provides a powerful tool for calculation not only critical exponents but also the free energy, correlation functions, structure factor and other quantities near the critical points. The approximate treatments of lattice models can be tested comparing the results with exact solutions of a limited set of 2-dimensional models as Ising model, hard hexagon or three state Potts model, eight vertex model and four state Potts model.