FIRST PRINCIPLES SIMULATION OF GRAIN-BOUNDARY SLIDING

We present the results of a total-energy pseudopotential simulation of the sliding process at a Sigma = 5 (001) twist grain boundary in germ anium. Sliding involves a stick-slip mechanism with local rebonding am ong a few atoms, accompanied by the clearance of gap states. At large strain, spreading of disorder from the boundary interface produces a l oss of strength in the system and would induce fracture. Finally we in vestigate the effects of temperature and strain rate on the sliding be havior.