COMPUTER-SIMULATION OF CORE STRUCTURE AND PEIERLS STRESS OF DISLOCATIONS IN ANTHRACENE-CRYSTALS

The equilibrium configuration for the core of a [010] screw dislocatio n in an anthracene crystal was calculated using the atom-atom potentia l method. It was strongly anisotropic and complicated due to the chara cteristic shape and dimension of the molecule. The core region did not spread as much as that of a [010](001) edge dislocation. Its energy w as lower than that of the edge dislocation. The Peierls stresses of bo th the edge and the screw dislocations were estimated by means of grad ually increasing an external shear stress; that of the screw dislocati on was much larger than that of the edge dislocation.