"Mechanical and Thermodynamic Behavior of Silicon at the Atomic Level" Martin Z. Bazant Seminar given August 7, 1997 Institute for Theoretical and Applied Mechanics Czech Academy of Sciences, Prague, Czech Republic Abstract: In order to understand macroscopic phenomena in terms of the underlying atomic motions, a model for interatomic forces is required. It must be simple enough to permit large-scale computer simulations but sophisticated enough to capture the essential physics of chemical bonding. In silicon, this has proven to be a very difficult task, but theoretical progress is being made. First principles information about interatomic forces comes from an analysis of elasticity and cohesive energy versus volume curves. With such methods realistic and efficient models for silicon are derived and applied to plastic deformations and phase transitions of single crystals.