By using atomic relaxation techniques, dislocation dipoles of various sizes and orientations were studied for monolayers with Lennard-Jones potential and nearest-neighbor piece-wise linear force interactions. In the case of the Lennard-Jones potential system, the lower-energy vacancy dipoles had an energy which was mainly a function of the vacancy content of the dipole over a wide range of angles. There was a competition, between the elastic forces and the topological constraints, which favored the presence of a 5-fold coordinate vacancy at the center of each core. In the case of short-range piece-wise linear force interactions, the lattice usually compressed upon introducing a dislocation. This was a consequence of the soft core of the interaction potential. The interstitial dipoles were lower in energy. In the case of the long-range Lennard-Jones potential system, the dislocations were mobile whereas, in the case of the piece-wise linear force system, they were pinned.

B.Joós, Q.Ren, M.S.Duesbery: Surface Science, 1994, 302[3], 385-94