A Reciprocal Space Approach for Locating Symmetry Elements in Patterson Superposition Maps

A Reciprocal Space Approach for Locating Symmetry Elements in Patterson Superposition Maps
Author:
Publisher:
Total Pages: 187
Release: 1990
Genre:
ISBN:

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A method for determining the location and possible existence of symmetry elements in Patterson superposition maps has been developed. A comparison of the original superposition map and a superposition map operated on by the symmetry element gives possible translations to the location of the symmetry element. A reciprocal space approach using structure factor-like quantities obtained from the Fourier transform of the superposition function is then used to determine the best'' location of the symmetry element. Constraints based upon the space group requirements are also used as a check on the locations. The locations of the symmetry elements are used to modify the Fourier transform coefficients of the superposition function to give an approximation of the structure factors, which are then refined using the EG relation. The analysis of several compounds using this method is presented. Reciprocal space techniques for locating multiple images in the superposition function are also presented, along with methods to remove the effect of multiple images in the Fourier transform coefficients of the superposition map. In addition, crystallographic studies of the extended chain structure of (NHC5H5)SbI4 and of the twinning method of the orthorhombic form of the high-{Tc} superconductor YBa2Cu3O{sub 7-x} are presented. 54 refs.

Energy Research Abstracts

Energy Research Abstracts
Author:
Publisher:
Total Pages: 498
Release: 1990
Genre: Power resources
ISBN:

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Chemical Abstracts

Chemical Abstracts
Author:
Publisher:
Total Pages: 2598
Release: 1990
Genre: Chemical abstracts
ISBN:

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Determination of Organic Structures by Physical Methods V3

Determination of Organic Structures by Physical Methods V3
Author: F.C. Nachod
Publisher: Elsevier
Total Pages: 489
Release: 2012-12-02
Genre: Science
ISBN: 032314845X

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Determination of Organic Structures by Physical Methods, Volume 3 is a seven-chapter text that describes the refinements of some established physical methods for organic structure determination. Each chapter of this book examines specific physical method, including photoelectron spectroscopy, X-ray diffraction, optical rotary dispersion, circular dichroism, mass spectrometry, and electron spin resonance and NMR spectroscopies. The historical developments, instrumentation, and applications to organic chemistry of these methods are discussed. This work will be of value to organic and analytical chemists and researchers.

International Tables for Crystallography, Volume B

International Tables for Crystallography, Volume B
Author: Uri Shmueli
Publisher: Springer Science & Business Media
Total Pages: 704
Release: 2008-08-27
Genre: Science
ISBN: 9781402082054

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International Tables for Crystallography are no longer available for purchase from Springer. For further information please contact Wiley Inc. (follow the link on the right hand side of this page). Volume B presents accounts of the numerous aspects of reciprocal space in crystallographic research. After an introductory chapter, Part 1 presents the reader with an account of structure-factor formalisms, an extensive treatment of the theory, algorithms and crystallographic applications of Fourier methods, and fundamental as well as advanced treatments of symmetry in reciprocal space. In Part 2, these general accounts are followed by detailed expositions of crystallographic statistics, the theory of direct methods, Patterson techniques, isomorphous replacement and anomalous scattering, and treatments of the role of electron microscopy and diffraction in crystal structure determination, including applications of direct methods to electron crystallography. Part 3 deals with applications of reciprocal space to molecular geometry and `best'-plane calculations, and contains a treatment of the principles of molecular graphics and modelling and their applications. A convergence-acceleration method of importance in the computation of approximate lattice sums is presented and the part concludes with a discussion of the Ewald method. Part 4 contains treatments of various diffuse-scattering phenomena arising from crystal dynamics, disorder and low dimensionality (liquid crystals), and an exposition of the underlying theories and/or experimental evidence. Polymer crystallography and reciprocal-space images of aperiodic crystals are also treated. Part 5 of the volume contains introductory treatments of the theory of the interaction of radiation with matter (dynamical theory) as applied to X-ray, electron and neutron diffraction techniques. The simplified trigonometric expressions for the structure factors in the 230 three-dimensional space groups, which appeared in Volume I of International Tables for X-ray Crystallography, are now given in Appendix 1.4.3 to Chapter 1.4 of this volume. Volume B is a vital addition to the library of scientists engaged in crystal structure determination, crystallographic computing, crystal physics and other fields of crystallographic research. Graduate students specializing in crystallography will find much material suitable for self-study and a rich source of references to the relevant literature.

Biomolecular Crystallography

Biomolecular Crystallography
Author: Bernhard Rupp
Publisher: Garland Science
Total Pages: 832
Release: 2009-10-20
Genre: Science
ISBN: 1134064195

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Synthesizing over thirty years of advances into a comprehensive textbook, Biomolecular Crystallography describes the fundamentals, practices, and applications of protein crystallography. Illustrated in full-color by the author, the text describes mathematical and physical concepts in accessible and accurate language. Biomolecular Crystallography will be a valuable resource for advanced undergraduate and graduate students and practitioners in structural biology, crystallography, and structural bioinformatics.