issue contents

ISSN: 2053-2733

November 2011 issue

Highlighted illustration

Cover illustration: Polar mode GM6 (left) and antiferrodistortive mode M3-1q (right) present in the monoclinic structure of SrAl2O4, together with a graph of maximal subgroups showing their isotropy subgroups. The amplitude of mode GM6 is much larger, and ab initio calculations confirm its soft character, while distortion M3-1q is a hard mode frozen as an induced secondary distortion [Perez-Mato et al. (2010). Acta Cryst. A66, 558-590]. The mode figures were drawn using FullProf Studio [Rodriguez-Carvajal (1993). Physica B, 192, 55-69].

research papers

link to html
A novel fast Fourier transform method is described for calculating powder diffraction patterns from crystal structural data. By also taking the Patterson symmetry of crystal structures into account, computational times can be reduced by an order of magnitude, thereby facilitating the application of the Debye scattering equation to microcrystallites.

link to html
A full classification of the Delaunay simplex forms has been performed which involve the structure of ice Ih and ice Ic.

link to html
Beq is a well defined entity that represents one property, mean-square displacement, of the anisotropic atomic displacement parameter tensor from which it is derived. Beq is not, however, the best estimate of the B factor that would result from isotropic model refinement. A new entity Best is proposed to serve this purpose.

link to html
An orientation method based on the intersection arcs of continuous diffraction patterns is described and is shown to perform well on simulated patterns of single-particle diffraction experiments performed at X-ray free-electron laser sources.

link to html
Theoretical analysis and experimental validation prove that a multi-dataset data-collection strategy produces better diffraction data. The readiness test is a simple and sensitive method for X-ray data-collection system evaluation and a benchmark.

link to html
Experimentally obtained and computer-simulated X-ray six-beam pinhole topographs based on the n-beam Takagi–Taupin (T–T) equation are reported for a channel-cut silicon crystal. It has been clarified that the algorithm to integrate the n-beam T–T equation can calculate the X-ray wavefield in a crystal of complex shape.

short communications

link to html
A method of calculating the polarization state of X-rays transmitted through a rotating four-quadrant X-ray phase retarder system is described using Jones calculus.

link to html
Computer-simulated pinhole topographs for spherical silicon crystals are reported and compared with those for parallel-plate crystals.

book reviews

international union of crystallography

Follow Acta Cryst. A
Sign up for e-alerts
Follow Acta Cryst. on Twitter
Follow us on facebook
Sign up for RSS feeds