issue contents

ISSN: 2053-2733

November 2010 issue

Highlighted illustration

Cover illustration: A collage of related patterns that are formed via tilings of the hyperbolic plane. Two-dimensional `universal tilings' (e.g. UQC473) of hyperbolic space can be wrapped onto a three-periodic minimal surface (e.g. the  gyroid), forming a curvilinear `Epinet tiling' (EGC473) whose edges relax to give a `Systre net', sqc14527. This approach to net enumeration is described in Ramsden et al. [Acta Cryst. (2009), A65, 81-108]. Further examples are collected at


Acta Cryst. (2010). A66, 631
doi: 10.1107/S0108767310041504
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The 2009 impact factor for Acta Crystallographica Section A is discussed.

research papers

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Relative scaling of light-on and light-off data from photocrystallographic experiments and the correction for temperature differences between the two data sets are discussed.

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Periodic tilings by polyhedra with five- and six-sided faces with up to 11 kinds of vertex in the tiling are described.

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The influence of multiple diffuse scattering effects upon the reflection and transmission coefficients in the case of grazing X-ray specular scattering from statistically rough surfaces is investigated. The statistical properties of the rough surface are described in terms of the r.m.s. roughness σ and correlation length ξ of the two-point height–height correlation function.

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An approach based on irreducible representations of the paramagnetic space group is used to find the ordering of magnetic moments induced by a magnetic phase transition. The combination of representation analysis and magnetic symmetry is the most effective way to analyze magnetic ordering and refine magnetic structures.

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The influence of different Student's T mosaic distributions upon the integrated reflection power ratio and the secondary extinction factor in mosaic crystals is presented.

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The double-slit dynamical diffraction of X-rays in perfect crystals is theoretically investigated. It is shown that interference fringes similar to Young's fringes are formed on the exit surface of a crystal.

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Exact probability density functions of the average (A) and difference (D) intensities of Friedel opposites have been derived and were favourably compared with histograms of A and D, which were simulated as well as recalculated from a published solved P1 structure.

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The limits of significance due to Poisson statistics have been investigated and theoretical agreement factors were calculated which may serve as benchmark values.

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Energy-filtered convergent-beam electron diffraction patterns of Si were obtained by transmission electron microscopy at different temperatures. Off-axis multi-beam orientations offer improved accuracy for simultaneous refinements of multiple structure factors and Debye–Waller factors, which is attributed to strong dynamical interactions between diffracted beams with each other and the transmitted beam.

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Debye–Waller and structure factors for B2 ordered simple cubic NiAl were obtained from elastically filtered off-zone-axis multi-beam convergent-beam electron diffraction patterns at different temperatures. The Debye–Waller factors for Al and Ni were shown to be equal at a cross-over temperature of ~90 K.

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X-ray diffraction peak profiles are calculated by the Monte Carlo method for different types of dislocation correlations. General conditions for screening of the long-range dislocation strain are derived and implemented.

short communications

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Orientations deviating from an ideal orientation by angles not exceeding a fixed limit constitute a ball. A formula for the volume of the intersection of two such balls is derived.


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Obituary for David H. Templeton.

international union of crystallography

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