The structure factor is calculated for the Nelson and Halperin model of the hexatic phase as a two-dimensional crystal containing a gas of interacting dislocations. It is shown that the diffraction peaks are Gaussians in the azimuthal direction. The azimuthal and the radial peak widths are expressed in terms of the elastic moduli and the mean dislocation density and do not involve any phenomenological parameter. The ratio of the radial to the azimuthal peak widths decreases considerably when the dislocations interact and depends on the sample size.

• Received 21 December 1993

DOI:https://doi.org/10.1103/PhysRevLett.73.102