This book is an introduction to the application of computer simulation and theory in the study of the interaction of energetic particles (1 ev to the MeV range) with solid surfaces. The authors describe methods that are applicable both to hard collisions between nuclear cores of atoms down to soft interactions, where chemical effects or long-range forces dominate. The range of potential applications of the technique is enormous. In surface science, applications include surface atomic structure determination using ion scattering spectroscopy or element analysis using SIMS or other techniques...