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CAPOW: a standalone program for the calculation of optimal weighting parameters for least-squares crystallographic refinements

Lookup NU author(s): Natalie Johnson, Professor Mike ProbertORCiD



This work is licensed under a Creative Commons Attribution 4.0 International License (CC BY 4.0).


The rigorous analysis of crystallographic models, refined through the use of least-squares minimization, is founded on the expectation that the data provided have a normal distribution of residuals. Processed single-crystal diffraction data rarely exhibit this feature without a weighting scheme being applied. These schemes are designed to reflect the precision and accuracy of the measurement of observed reflection intensities. While many programs have the ability to calculate optimal parameters for applied weighting schemes, there are still programs that do not contain this functionality, particularly when moving beyond the spherical atom model. For this purpose, CAPOW (calculation and plotting of optimal weights), a new program for the calculation of optimal weighting parameters for a SHELXL weighting scheme, is presented and an example of its application in a multipole refinement is given.

Publication metadata

Author(s): Johnson NT, Ott H, Probert MR

Publication type: Article

Publication status: Published

Journal: Journal of Applied Crystallography

Year: 2018

Volume: 51

Issue: 1

Pages: 200-204

Print publication date: 01/02/2018

Acceptance date: 17/11/2017

Date deposited: 08/02/2018

ISSN (print): 0021-8898

ISSN (electronic): 1600-5767

Publisher: Wiley on behalf of International Union of Crystallography


DOI: 10.1107/S1600576717016600


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