Acta Crystallographica Section A

Foundations and Advances

Volume 70, Part 5 (September 2014)



[Issue Author Index][Volume Author Index]
[Cover illustration] Cover illustration: Combined analysis, a global approach for quantitative determination of crystallite sizes and shapes, crystallographic texture and structural refinements, is extended to electron powder diffraction patterns and used to characterize nanoparticles in the form of powders and thin films [Boullay et al. (2014). Acta Cryst. A70, 448-456].

foundations


foundations


research papers


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Acta Cryst. (2014). A70, 417-428  [ doi:10.1107/S2053273314007712 ]

On the subgroup structure of the hyperoctahedral group in six dimensions

E. Zappa, E. C. Dykeman and R. Twarock

Synopsis: The subgroup structure of the hyperoctahedral group in six dimensions is studied, with particular attention to the subgroups isomorphic to the icosahedral group. The orthogonal crystallographic representations of the icosahedral group are classified, and their intersections are studied in some detail, using a combinatorial approach which involves results from graph theory and their spectra.

Online 10 July 2014


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Acta Cryst. (2014). A70, 429-440  [ doi:10.1107/S205327331400802X ]

Multiple Bragg reflection by a thick mosaic crystal

J. Wuttke

Synopsis: To investigate multiple Bragg reflections from a thick and ideally imperfect crystal, the Darwin-Hamilton equations are generalized. Out-of-plane wavevector diffusion causes a noticeable shift and distortion of rocking curves.

Online 10 July 2014


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Acta Cryst. (2014). A70, 441-447  [ doi:10.1107/S2053273314009218 ]

Octagonal symmetry in low-discrepancy [beta]-manganese

W. Hornfeck and P. Kuhn

Synopsis: A low-discrepancy cubic variant of [beta]-Mn is presented, exhibiting local octagonal symmetry upon projection. A comparison of the actual and ideal structure models of [beta]-Mn is made in terms of the newly devised concept of geometrical discrepancy maps. Geometrical discrepancy maps combine predictive and discriminatory powers to appear useful within a wide range of structural chemistry studies.

Online 10 July 2014


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Acta Cryst. (2014). A70, 448-456  [ doi:10.1107/S2053273314009930 ]

Fast microstructure and phase analyses of nanopowders using combined analysis of transmission electron microscopy scattering patterns

P. Boullay, L. Lutterotti, D. Chateigner and L. Sicard

Synopsis: The usefulness of combined analysis for fast determination of crystallite sizes and shapes of nanoparticle aggregates using electron diffraction patterns is demonstrated.

Online 17 July 2014


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Acta Cryst. (2014). A70, 457-471  [ doi:10.1107/S2053273314011139 ]

Strain distributions and diffraction peak profiles from crystals with dislocations

V. M. Kaganer and K. K. Sabelfeld

Synopsis: Diffraction profiles for different models of dislocation arrangements are calculated directly by the Monte Carlo method and compared with the strain distributions for the same arrangements, which corresponds to the Stokes-Wilson approximation. The strain distributions and the diffraction profiles are in close agreement as long as long-range order is absent.

Online 17 July 2014


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Acta Cryst. (2014). A70, 472-482  [ doi:10.1107/S2053273314011140 ]

Radial spacing distributions from planar point sets

M. Baake, F. Götze, C. Huck and T. Jakobi

Synopsis: The radial projection method for locally finite planar point sets is explored and numerical examples for different types of order are provided.

Online 30 August 2014


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Acta Cryst. (2014). A70, 483-498  [ doi:10.1107/S2053273314012443 ]

Hirshfeld atom refinement for modelling strong hydrogen bonds

M. Woinska, D. Jayatilaka, M. A. Spackman, A. J. Edwards, P. M. Dominiak, K. Wozniak, E. Nishibori, K. Sugimoto and S. Grabowsky

Synopsis: Different X-ray refinement methods for modelling hydrogen bonds in the compound L-phenylalaninium hydrogen maleate are compared. It is found that Hirshfeld atom refinement (HAR) produces bond lengths involving hydrogen atoms in agreement with benchmarking results from neutron diffraction, and it is the only X-ray method to obtain a symmetric hydrogen site in the intramolecular hydrogen bond of this compound. Residual-density distributions in HAR are better than in the multipole-based models.

Online 30 August 2014


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Acta Cryst. (2014). A70, 499-513  [ doi:10.1107/S2053273314012984 ]

More about systematic errors in charge-density studies

J. Henn and K. Meindl

Synopsis: Methods for the detection and visualization of systematic errors in measurement data are developed on the basis of conditional probabilities and applied to artificial and experimental data from the literature.

Online 30 August 2014


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Acta Cryst. (2014). A70, 514-517  [ doi:10.1107/S2053273314013229 ]

Analysis of multicrystal pump-probe data sets. I. Expressions for the RATIO model

B. Fournier and P. Coppens

Synopsis: The application of the RATIO method in processing/analysis prior to structure refinement requires an appropriate ratio model for modeling the light response. Such a model is discussed, taking into account both geometric and thermal light-induced changes.

Online 30 August 2014


book reviews


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Acta Cryst. (2014). A70, 518-519  [ doi:10.1107/S2053273314010651 ]

Phasing in Crystallography: A Modern Perspective

Online 17 July 2014


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