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Pushing the limits of crystallography

A very serious concern of scientists dealing with crystal structure refinement, including theoretical research, pertains to the characteristic bias in calculated versus measured diffraction intensities, observed particularly in the weak reflection regime. This bias is here attributed to corrective f...

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Autores principales: Wolny, Janusz, Buganski, Ireneusz, Kuczera, Pawel, Strzalka, Radoslaw
Formato: Online Artículo Texto
Lenguaje:English
Publicado: International Union of Crystallography 2016
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5139996/
https://www.ncbi.nlm.nih.gov/pubmed/27980514
http://dx.doi.org/10.1107/S160057671601637X
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author Wolny, Janusz
Buganski, Ireneusz
Kuczera, Pawel
Strzalka, Radoslaw
author_facet Wolny, Janusz
Buganski, Ireneusz
Kuczera, Pawel
Strzalka, Radoslaw
author_sort Wolny, Janusz
collection PubMed
description A very serious concern of scientists dealing with crystal structure refinement, including theoretical research, pertains to the characteristic bias in calculated versus measured diffraction intensities, observed particularly in the weak reflection regime. This bias is here attributed to corrective factors for phonons and, even more distinctly, phasons, and credible proof supporting this assumption is given. The lack of a consistent theory of phasons in quasicrystals significantly contributes to this characteristic bias. It is shown that the most commonly used exponential Debye–Waller factor for phasons fails in the case of quasicrystals, and a novel method of calculating the correction factor within a statistical approach is proposed. The results obtained for model quasiperiodic systems show that phasonic perturbations can be successfully described and refinement fits of high quality are achievable. The standard Debye–Waller factor for phonons works equally well for periodic and quasiperiodic crystals, and it is only in the last steps of a refinement that different correction functions need to be applied to improve the fit quality.
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spelling pubmed-51399962016-12-15 Pushing the limits of crystallography Wolny, Janusz Buganski, Ireneusz Kuczera, Pawel Strzalka, Radoslaw J Appl Crystallogr Research Papers A very serious concern of scientists dealing with crystal structure refinement, including theoretical research, pertains to the characteristic bias in calculated versus measured diffraction intensities, observed particularly in the weak reflection regime. This bias is here attributed to corrective factors for phonons and, even more distinctly, phasons, and credible proof supporting this assumption is given. The lack of a consistent theory of phasons in quasicrystals significantly contributes to this characteristic bias. It is shown that the most commonly used exponential Debye–Waller factor for phasons fails in the case of quasicrystals, and a novel method of calculating the correction factor within a statistical approach is proposed. The results obtained for model quasiperiodic systems show that phasonic perturbations can be successfully described and refinement fits of high quality are achievable. The standard Debye–Waller factor for phonons works equally well for periodic and quasiperiodic crystals, and it is only in the last steps of a refinement that different correction functions need to be applied to improve the fit quality. International Union of Crystallography 2016-11-18 /pmc/articles/PMC5139996/ /pubmed/27980514 http://dx.doi.org/10.1107/S160057671601637X Text en © Janusz Wolny et al. 2016 http://creativecommons.org/licenses/by/2.0/uk/ This is an open-access article distributed under the terms of the Creative Commons Attribution Licence, which permits unrestricted use, distribution, and reproduction in any medium, provided the original authors and source are cited.
spellingShingle Research Papers
Wolny, Janusz
Buganski, Ireneusz
Kuczera, Pawel
Strzalka, Radoslaw
Pushing the limits of crystallography
title Pushing the limits of crystallography
title_full Pushing the limits of crystallography
title_fullStr Pushing the limits of crystallography
title_full_unstemmed Pushing the limits of crystallography
title_short Pushing the limits of crystallography
title_sort pushing the limits of crystallography
topic Research Papers
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5139996/
https://www.ncbi.nlm.nih.gov/pubmed/27980514
http://dx.doi.org/10.1107/S160057671601637X
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