Analysis and characterization of data from twinned crystals.

@article{Chandra1999AnalysisAC,
  title={Analysis and characterization of data from twinned crystals.},
  author={N Chandra and K. Ravi Acharya and Peter C. E. Moody},
  journal={Acta crystallographica. Section D, Biological crystallography},
  year={1999},
  volume={55 Pt 10},
  pages={
          1750-8
        }
}
It is difficult but not impossible to determine a macromolecular structure using X-ray data obtained from twinned crystals, providing it is noticed and corrected. For perfectly twinned crystals, the structure can probably only be solved by molecular replacement. It is possible to detect and characterize twinning from an analysis of the intensity statistics and crystal packing density. Tables of likely twinning operators and some examples are discussed here. 

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