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 32 and turned by 45°, separates phosphates and bases. The indices of the molecular forms are indicated. Courtesy of A. Janner.
An indexing scheme for decagonal quasicrystals, analogous to the Miller–Bravais indexing of hexagonal crystals, is proposed and compared with other decagonal schemes. The status of the zone law for decagonal quasicrystals is discussed and elucidated.
Multiple twinning in cubic crystals is represented geometrically by three-dimensional fractals and algebraically by groupoids. The groupoid composition table can be used to identify the Σ3n grain boundaries in EBSD maps.
Accurate structure factors of silicon and diamond have been determined from powder diffraction data measured at SPring-8, BL02B2. The accuracy of structure factors is evaluated. The usefulness of the present structure factors is also reported.
With Bragg peaks normalized to those of solid spheres of uniform electron density, a dual-space iteration-based algorithm is applied to successfully reconstruct hypothetical 500- and 1000-atom carbon cluster crystal structures at both high and low resolutions.
A transformational space-group symbol (TSG) composed of the well defined standard space-group identifier, an explicitly given axis system transformation and an origin shift is proposed to designate any space-group description.