Dislocations and the Commensurate-Incommensurate Transition in Two Dimensions

The incommensurate adsorbed solid is found to become unstable to dislocations when the lattice period approaches that of a sufficiently low-order commensurate phase such as a 2×1 rectangular overlayer or the (3×3)R 30° hexagonal structure which occurs for krypton on graphite. In these cases, a fluid phase is expected between the commensurate and incommensurate solids.