issue contents

ISSN: 2053-2733

November 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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The restrictions on the coefficients describing the piezoelectric effect of second order in stress or strain are given for all the orientations that can be expressed by the sequence of elements in the Hermann–Mauguin symbol of the crystal or quasicrystal point group.

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A new approach to the derivation of standard orientation-location parts of symmetry-operation symbols from symmetry matrices is described. The method is also applicable to the symmetry operations in non-conventional space-group settings and its standardization procedure may be used in other derivation techniques.

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The directional properties of electron–proton spin interaction in an external magnetic field give rise to an anisotropic distribution of the intensity of polarized neutron scattering from dynamically polarized protons of radical molecules in solution.

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Algorithms are presented for maximally efficient computation of the crystallographic fast Fourier transform (FFT). The approach is applicable to all 230 space groups and allows reduction in both the computation time and the memory usage by a factor equal to the number of symmetry operators. The central idea is a recursive reduction of the problem to a series of transforms on grids with no special points.

short communications

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An analytical expression for the characteristic length scale of the pair correlation functions for faulted hexagonal close-packed structures is derived.

book reviews

Acta Cryst. (2007). A63, 483
doi: 10.1107/S0108767307041207

international union of crystallography

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