Acta Crystallographica Section A
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Acta Crystallographica Section A: Foundations and Advances covers theoretical and fundamental aspects of the structure of matter. The journal is the prime forum for research in diffraction physics and the theory of crystallographic structure determination by diffraction methods using X-rays, neutrons and electrons. The structures include periodic and aperiodic crystals, and non-periodic disordered materials, and the corresponding Bragg, satellite and diffuse scattering, thermal motion and symmetry aspects. Spatial resolutions range from the subatomic domain in charge-density studies to nanodimensional imperfections such as dislocations and twin walls. The chemistry encompasses metals, alloys, and inorganic, organic and biological materials. Structure prediction and properties such as the theory of phase transformations are also covered.enCopyright (c) 2016 International Union of Crystallography2016-05-17International Union of CrystallographyInternational Union of Crystallographyhttp://journals.iucr.orgurn:issn:2053-2733Acta Crystallographica Section A: Foundations and Advances covers theoretical and fundamental aspects of the structure of matter. The journal is the prime forum for research in diffraction physics and the theory of crystallographic structure determination by diffraction methods using X-rays, neutrons and electrons. The structures include periodic and aperiodic crystals, and non-periodic disordered materials, and the corresponding Bragg, satellite and diffuse scattering, thermal motion and symmetry aspects. Spatial resolutions range from the subatomic domain in charge-density studies to nanodimensional imperfections such as dislocations and twin walls. The chemistry encompasses metals, alloys, and inorganic, organic and biological materials. Structure prediction and properties such as the theory of phase transformations are also covered.text/htmlActa Crystallographica Section A: Foundations and Advances, Volume 72, Part 4, 2016textweekly62002-01-01T00:00+00:004722016-05-17Copyright (c) 2016 International Union of CrystallographyActa Crystallographica Section A: Foundations and Advances459urn:issn:2053-2733med@iucr.orgMay 20162016-05-17Acta Crystallographica Section Ahttp://journals.iucr.org/logos/rss10a.gif
http://journals.iucr.org/a/issues/2016/04/00/isscontsbdy.html
Still imageFaces of root polytopes in all dimensions
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In this paper the root polytopes of all finite reflection groups W with a connected Coxeter–Dynkin diagram in {\bb R}^n are identified, their faces of dimensions 0 ≤ d ≤ n − 1 are counted, and the construction of representatives of the appropriate W-conjugacy class is described. The method consists of recursive decoration of the appropriate Coxeter–Dynkin diagram [Champagne et al. (1995). Can. J. Phys. 73, 566–584]. Each recursion step provides the essentials of faces of a specific dimension and specific symmetry. The results can be applied to crystals of any dimension and any symmetry.Copyright (c) 2016 International Union of Crystallographyurn:issn:2053-2733Szajewska, M.2016-05-13doi:10.1107/S2053273316004551International Union of CrystallographyThe reflection group W can be specified by a connected Coxeter–Dynkin diagram consisting of either one or two orbits of W. An individual orbit is viewed as the set of vertices of a polytope (root polytope) generated by its W from any one point of the orbit.ENfinite Coxeter groupsroot polytopesLie groupsLie algebraIn this paper the root polytopes of all finite reflection groups W with a connected Coxeter–Dynkin diagram in {\bb R}^n are identified, their faces of dimensions 0 ≤ d ≤ n − 1 are counted, and the construction of representatives of the appropriate W-conjugacy class is described. The method consists of recursive decoration of the appropriate Coxeter–Dynkin diagram [Champagne et al. (1995). Can. J. Phys. 73, 566–584]. Each recursion step provides the essentials of faces of a specific dimension and specific symmetry. The results can be applied to crystals of any dimension and any symmetry.text/htmlFaces of root polytopes in all dimensionstext4722016-05-13Copyright (c) 2016 International Union of CrystallographyActa Crystallographica Section Aresearch papers00Properties of X-ray resonant scattering in the Bragg case revealed on the Riemann surface
http://scripts.iucr.org/cgi-bin/paper?td5033
Continuing the work described in the previous paper [Saka (2016). Acta Cryst. A72, 338–348], the dynamical theory for perfect crystals in the Bragg case is reformulated using the Riemann surface. In particular, diffraction under resonant scattering conditions is investigated. The characteristic features of the dispersion surface and the rocking curve are analytically revealed using four parameters, which are the real and imaginary parts of two quantities specifying the degree of departure from the exact Bragg conditions and the reflection strength. Characteristic properties that have been deduced through numerical analysis are derived analytically using these four parameters. Visualization of the geometric relationships between the four parameters on the Riemann surface is useful for understanding many properties such as symmetry and sharpness of the rocking curve under special conditions. Therefore, employing the Riemann surface is instructive for numerical analysis and useful for understanding dynamical diffraction in the Bragg case.Copyright (c) 2016 International Union of Crystallographyurn:issn:2053-2733Saka, T.2016-05-13doi:10.1107/S2053273316005404International Union of CrystallographyProperties of X-ray resonant scattering in the Bragg case are revealed analytically using the Riemann surface.ENX-ray diffractiondynamical theoryBragg caseRiemann surfacedispersion surfacerocking curveresonant scatteringContinuing the work described in the previous paper [Saka (2016). Acta Cryst. A72, 338–348], the dynamical theory for perfect crystals in the Bragg case is reformulated using the Riemann surface. In particular, diffraction under resonant scattering conditions is investigated. The characteristic features of the dispersion surface and the rocking curve are analytically revealed using four parameters, which are the real and imaginary parts of two quantities specifying the degree of departure from the exact Bragg conditions and the reflection strength. Characteristic properties that have been deduced through numerical analysis are derived analytically using these four parameters. Visualization of the geometric relationships between the four parameters on the Riemann surface is useful for understanding many properties such as symmetry and sharpness of the rocking curve under special conditions. Therefore, employing the Riemann surface is instructive for numerical analysis and useful for understanding dynamical diffraction in the Bragg case.text/htmlProperties of X-ray resonant scattering in the Bragg case revealed on the Riemann surfacetext4722016-05-13Copyright (c) 2016 International Union of CrystallographyActa Crystallographica Section Aresearch papers00Crystal Clear. The Autobiographies of Sir Lawrence & Lady Bragg. Edited by A. M. Glazer and Patience Thomson. Oxford University Press, 2015. Pp. xx + 427. Hardback. Price GBP 35.00. ISBN 978-0-19-874430-6.
http://scripts.iucr.org/cgi-bin/paper?xo0024
Copyright (c) 2016 International Union of Crystallographyurn:issn:2053-2733Ferraris, G.2016-05-13doi:10.1107/S2053273315024018International Union of CrystallographyENbook reviewSir William Lawrence BraggAlice Grace Jenny Braggtext/htmlCrystal Clear. The Autobiographies of Sir Lawrence & Lady Bragg. Edited by A. M. Glazer and Patience Thomson. Oxford University Press, 2015. Pp. xx + 427. Hardback. Price GBP 35.00. ISBN 978-0-19-874430-6.text4722016-05-13Copyright (c) 2016 International Union of CrystallographyActa Crystallographica Section Abook reviews00Perspectives in Crystallography. By John R. Helliwell. CRC Press, 2016. Hardback, Pp. xv + 155. Price GBP 75.65. ISBN 978-1-4987-3210-9.
http://scripts.iucr.org/cgi-bin/paper?xo0047
Copyright (c) 2016 International Union of Crystallographyurn:issn:2053-2733Ferraris, G.2016-05-13doi:10.1107/S2053273316003831International Union of CrystallographyENbook reviewbiocrystallographysynchrotron radiationtext/htmlPerspectives in Crystallography. By John R. Helliwell. CRC Press, 2016. Hardback, Pp. xv + 155. Price GBP 75.65. ISBN 978-1-4987-3210-9.text4722016-05-13Copyright (c) 2016 International Union of CrystallographyActa Crystallographica Section Abook reviews00