International
Tables for
Crystallography
Volume F
Crystallography of biological macromolecules
Edited by M. G. Rossmann and E. Arnold

International Tables for Crystallography (2006). Vol. F, ch. 11.4, p. 233   | 1 | 2 |

Section 11.4.9. Global refinement or post refinement

Z. Otwinowskia* and W. Minorb

aUT Southwestern Medical Center at Dallas, 5323 Harry Hines Boulevard, Dallas, TX 75390-9038, USA, and bDepartment of Molecular Physiology and Biological Physics, University of Virginia, 1300 Jefferson Park Avenue, Charlottesville, VA 22908, USA
Correspondence e-mail:  zbyszek@mix.swmed.edu

11.4.9. Global refinement or post refinement

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The process of refining crystal parameters using the combined reflection intensity measurements is known as global refinement or post refinement (Rossmann, 1979[link]; Evans, 1993[link]). The implementation of this method in SCALEPACK allows for separate refinement of the orientation of each image, but with the same unit-cell value for the whole data set. In each batch of data (a batch is typically one image), different unit-cell parameters may be poorly determined. However, in a typical data set, there are enough orientations to determine all unit-cell lengths and angles precisely. Global refinement is also more precise than the processing of a single image in the determination of crystal mosaicity and the orientation of each image.

References

Evans, P. (1993). Data reduction: data collection and processing. In Proceedings of the CCP4 study weekend. Data collection and processing, 29–30 January, edited by L. Sawyer, N. Isaac & S. Bailey, pp. 114–123. Warrington: Daresbury Laboratory.
Rossmann, M. G. (1979). Processing oscillation diffraction data for very large unit cells with an automatic convolution technique and profile fitting. J. Appl. Cryst. 12, 225–238.








































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