DISLOCATION CORE-CORE INTERACTION AND PEIERLS STRESS IN A MODEL HEXAGONAL LATTICE

A series of atomistic calculations is performed in order to explore di slocation core-core interactions and the Peierls stress in a model hex agonal lattice. The method of calculation is the lattice Green's funct ion method, using several pair potentials with variable parameters. We confirm that dislocation cores broaden as a pair of dislocations with opposite sign move closer to each other. Continuum theories are surpr isingly accurate in describing the dislocation-dislocation interaction force even in the range of strong core-core overlap. However, our ato mistic calculations show that while the relation between the Peierls s tress and dislocation width is exponential as the Parleys-Nabarro mode predicts, that model underestimates the Parleys stress by nearly a fa ctor of 10(4).