Dislocations in two dimensions I. Floating systems

Abstract

The properties of defects in condensed two-dimensional lattices of the inert gases Kr and Xe are examined by computer simulation, with a view to understanding the properties of defects in a novel crystal structure—the triangular lattice. Generalized stacking faults, point defects and dislocation dipoles are considered; the energies, mechanical properties and geometric configurations are calculated. It is found that dislocation dipoles with small separations tend to behave like point-defect clusters. Large dipoles show the expected elastic energy dependence, but interact strongly with the lattice, and have significant Peierls stresses. The defect properties are found to depend principally on the state of lattice expansion or compression. The participation of dislocations in the melting transition is considered; continuous melting via a dislocation-mediated mechanism is found to be unlikely.