issue contents

ISSN: 2053-2733

May 2007 issue

Highlighted illustration

Cover illustration: The molecular form of the guanosine-5'-phosphate tetramer [Zimmerman (1976). J. Mol. Biol. 106, 663-672] has vertices at points of a cubic lattice with parameter a defined by the distance of O6 from the centre. The height is H = 2a and the basis a square scaled by a factor 6 from the central hole. Another square, scaled by 3[square root]2 and turned by 45°, separates phosphates and bases. The indices of the molecular forms are indicated. Courtesy of A. Janner.

research papers

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Identification of the composition planes of the inversion boundary in ZnO ceramics by the use of the standard stereographic projection technique and the electron back-scattered diffraction.

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A possible model of one-electron reduced density matrices is presented. Potential benefits from a joint refinement of the model from X-ray diffraction and deep inelastic scattering data are illustrated.

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A scheme is proposed, the phase and amplitude recovery and diffraction image generation method (PARADIGM), for the direct determination of the three-dimensional electron density of a surface unit cell from surface X-ray diffraction (SXRD) data. The method is illustrated by solving the previously unknown (multidomain) surface structure of Sb/Au(110)–√3 × √3R54.7°.

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The peak width of multiple diffraction events is derived by means of purely geometrical considerations in reciprocal space from the divergence and wavelength spread of the incident beam and the mosaic spread and magnitude of the perfect crystallites in the sample.

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A rigorous derivation of the mean-square Friedel intensity difference for pseudo-centrosymmetric structures leads to formulae useful in absolute-structure determination and structure solution by resonant-scattering techniques.

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The restrictions on the form of property tensors of rank ≤4 that follow from the Neumann principle for the point groups describing quasicrystals are deduced from those for the point groups describing ordinary crystals.

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X-ray diffraction from homogeneously bent crystals is studied within the interbranch resonance concept for large gradient. It is predicted that prominent extinction effects occur due to the interbranch phase changes of the wavefields.

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The calculation of the twin index and the evaluation of the lattice pseudo-symmetry in manifold twins are revised. Some inconsistencies in the literature are addressed.

addenda and errata

Acta Cryst. (2007). A63, 287
doi: 10.1107/S0108767307016248

books received

Acta Cryst. (2007). A63, 288
doi: 10.1107/S010876730701149X

Acta Cryst. (2007). A63, 288
doi: 10.1107/S0108767307011506
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