Analysing Friedel averages and differences

Simon Parsons; Phillip Pattison; Howard D. Flack

doi:10.1107/S0108767312034885

Analysing Friedel averages and differences

Simon Parsons, Phillip Pattison, Howard D. Flack

Research output: Contribution to journal › Article › peer-review

Abstract

Various practical applications of the average (A) and difference (D) of Friedel opposites are described. Techniques based on the resonant-scattering contribution to Friedel differences are applied to see whether a crystal is centrosymmetric or not, and to determine the point group of the crystal. For the validation of a structural study, plots of A_obs against A_model, and D_obs against Dm_odel are used extensively. Moreover, it is useful to display both plots on the same graph. Intensity measurements on a crystal of NaClO₃ were made at three different speeds, with two different radiations and two different diffractometers, and treated with two different software packages and four different absorption corrections. The evaluation of these numerous data sets reveals underlying deficiencies. For comparison, plots of A_obsagainst A_model, and D_obs against D_model are presented for two centrosymmetric crystals.

Original language	English
Pages (from-to)	736-749
Journal	Acta Crystallographica Section A: Foundations of Crystallography
Volume	68
Issue number	6
DOIs	https://doi.org/10.1107/S0108767312034885
Publication status	Published - 1 Nov 2012

Keywords / Materials (for Non-textual outputs)

absolute structure
Friedel differences
R(merge)
R(int)

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10.1107/S0108767312034885

Analysing Friedel averages and differences
Copyright © 2012 International Union of Crystallography. All rights reserved.
Final published version, 1.37 MB

http://scripts.iucr.org/cgi-bin/paper?S0108767312034885

Pressure Sensitive Complexformation based on self assembling ligands
Parsons, S., Jones, A., Kamenev, K. & Tasker, P.
EPSRC
1/03/09 → 29/08/12
Project: Research

Cite this

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title = "Analysing Friedel averages and differences",

abstract = "Various practical applications of the average (A) and difference (D) of Friedel opposites are described. Techniques based on the resonant-scattering contribution to Friedel differences are applied to see whether a crystal is centrosymmetric or not, and to determine the point group of the crystal. For the validation of a structural study, plots of Aobs against Amodel, and Dobs against Dmodel are used extensively. Moreover, it is useful to display both plots on the same graph. Intensity measurements on a crystal of NaClO3 were made at three different speeds, with two different radiations and two different diffractometers, and treated with two different software packages and four different absorption corrections. The evaluation of these numerous data sets reveals underlying deficiencies. For comparison, plots of Aobs against Amodel, and Dobs against Dmodel are presented for two centrosymmetric crystals.",

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AU - Pattison, Phillip

AU - Flack, Howard D.

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N2 - Various practical applications of the average (A) and difference (D) of Friedel opposites are described. Techniques based on the resonant-scattering contribution to Friedel differences are applied to see whether a crystal is centrosymmetric or not, and to determine the point group of the crystal. For the validation of a structural study, plots of Aobs against Amodel, and Dobs against Dmodel are used extensively. Moreover, it is useful to display both plots on the same graph. Intensity measurements on a crystal of NaClO3 were made at three different speeds, with two different radiations and two different diffractometers, and treated with two different software packages and four different absorption corrections. The evaluation of these numerous data sets reveals underlying deficiencies. For comparison, plots of Aobs against Amodel, and Dobs against Dmodel are presented for two centrosymmetric crystals.

AB - Various practical applications of the average (A) and difference (D) of Friedel opposites are described. Techniques based on the resonant-scattering contribution to Friedel differences are applied to see whether a crystal is centrosymmetric or not, and to determine the point group of the crystal. For the validation of a structural study, plots of Aobs against Amodel, and Dobs against Dmodel are used extensively. Moreover, it is useful to display both plots on the same graph. Intensity measurements on a crystal of NaClO3 were made at three different speeds, with two different radiations and two different diffractometers, and treated with two different software packages and four different absorption corrections. The evaluation of these numerous data sets reveals underlying deficiencies. For comparison, plots of Aobs against Amodel, and Dobs against Dmodel are presented for two centrosymmetric crystals.

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KW - Friedel differences

KW - R(merge)

KW - R(int)

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DO - 10.1107/S0108767312034885

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Analysing Friedel averages and differences

Abstract

Keywords / Materials (for Non-textual outputs)

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Projects

Pressure Sensitive Complexformation based on self assembling ligands

Cite this