Signatures of collective local and nanoscale distortions in diffraction experiments

The effects of periodic and aperiodic distortions on the structure factor and radial distribution function of single-component lattices are investigated. To this end, different kinds of distortions are applied to the otherwise perfect square lattice and the corresponding radial distribution function and structure factor for the resulting lattices are calculated. When the applied distortions have a periodic character, they are very easily recognized in the calculated structure factors as new superlattice peaks. However, when the periodicity of the distortions is suppressed, the signatures of disorder only show up as smooth and subtle features on the diffuse part of the scattering, making it very difficult to identify the nature of the distortions present in the lattice. The implications of these results are discussed.