Introduction to the atomic structure of surfaces:: the theoretical point of view

An introduction to surface atomic structure and vibrations is presented. After a brief recall of two-dimensional Bravais lattices, relaxation and reconstruction phenomena are discussed and interpreted qualitatively, both for clean and adsorbate covered surfaces. Then the principle of surface diffraction, which is the phenomenon at the basis of many experimental techniques for the determination of surface structure, is explained. Finally surface vibrations and their consequences on mean square displacements of surface atoms are studied.