ABSTRACT
Many interesting quantum effects appear at low temperatures due to the effect of quantum statistics. This chapter briefly reviews the experimental situation in surface adsorption phenomena with particular emphasis on quantum effects. It considers models for the computation of interaction potentials and examples. The chapter summarizes the basic formulae for path integral Monte Carlo and finite size scaling for critical phenomena. It presents examples for phase transitions and quantum effects in adsorbed layers. Phase diagrams of adsorbed He particles show interesting features which have many similarities to the phase diagrams of adsorbed hydrogen systems. The computation of equilibrium structures and phases of the system with several thousand atoms and all its electrons is still a problem which is far beyond tractability by present-day computers. Thus good approximative schemes or parameterizations of interaction potentials are important. Phase transitions in adsorbed layers often take place at low temperatures where quantum effects are important.
