A new vision for Acta Crystallographica Section A

The scope of Acta Crystallographica Section A is outlined and new section for high-impact articles, Advances, is announced.

Nets with collisions (unstable nets) and crystal chemistry

Examples are given of nets describing the topology of real crystal structures in which groups of vertices collide in barycentric coordinates and in high-symmetry embeddings.

Homometry in the light of coherent beams

Two systems are homometric if they are indistinguishable by diffraction. This article mainly discusses the issue of diffuse scattering homometry and its relation to high-order correlation functions. The study of the Rudin–Shapiro sequence, homometric to random sequences, allows one to manipulate independently two-point and four-point correlation functions, and to show their effect on the statistics of speckle patterns.

More about residual values

Predictions for residual values based on the experimental data and on knowledge of the number of model parameters used to fit the experimental data are presented. Applications to crystallographic residual values are discussed.

Direct phasing of nanocrystal diffraction

A new direct phasing method is introduced that exploits small shifts in the positions of Bragg peaks in a nanocrystal diffraction pattern.

Comparative study of X-ray charge-density data on CoSb₃

Experimental electron-density studies of inorganic, extended solids containing heavy elements are highly challenging. Such a study on a particularly problematic case, CoSb₃, is presented and discussed.

C₇₀, C₈₀, C₉₀ and carbon nanotubes by breaking of the icosahedral symmetry of C₆₀

The structure of particular hollow-cage fullerenes is described in exact coordinates, and their existence explained from a symmetry-breaking mechanism starting from the perfect icosahedral symmetry of C₆₀. The mechanism is extended to also describe the possible construction of larger nanostructures such as carbon nanotubes, as well as sets of stereoisomers of the C₆₀ molecule.

Platonic solids generate their four-dimensional analogues

A Clifford spinor construction shows how the Platonic solids induce their four-dimensional counterparts and determine their symmetries.

Distribution rules of systematic absences on the Conway topograph and their application to powder auto-indexing

Distribution rules of systematic absences applicable for powder auto-indexing are provided.

Spin line groups

Spin line groups, describing magnetic symmetries of quasi-one-dimensional systems, are studied and derived for the first family line groups. Corresponding spin arrangements are discussed and illustrated by several examples.

Incommensurate Crystallography

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