Cover illustration: A collage of related patterns that are formed via tilings of the hyperbolic plane. Two-dimensional `universal tilings' (e.g. UQC473) of hyperbolic space can be wrapped onto a three-periodic minimal surface (e.g. the gyroid), forming a curvilinear `Epinet tiling' (EGC473) whose edges relax to give a `Systre net', sqc14527. This approach to net enumeration is described in Ramsden et al. [Acta Cryst. (2009), A65, 81-108]. Further examples are collected at https://epinet.anu.edu.au.
A selection of papers from the CECAM/SimBioMa workshop on `Structural Transitions in Solids: Theory, Simulations, Experiments and Visualization Techniques' held in Lugano, 8–11 July 2009, are introduced.
An ensemble of crystal structures can be modeled as a set of points in a high-dimensional space (fingerprint space) equipped with a suitable distance measure. This modeling method allows the use of multidimensional data-analysis tools to extract unique results from runs of the evolutionary structure predictor USPEX and is a useful tool in the study of crystal-structure sets and global chemical features of the energy landscape.
The energy landscape concept, serving as the foundation of a deductive approach to solid-state chemistry, is applied to the theoretical prediction and synthetic realization of new crystalline compounds.
The nonlinear enhancement in energy storage capacity of polyvinylidene fluoride polymer is explained on the basis of a phase transition from nonpolar to polar structures. The energy storage capacity is found to be several times larger than existing polymer materials and to depend critically on copolymerization.
Symmetry-mode decomposition of displacive distorted structures and its applications are reviewed in the light of new freely available software. The advantages of a parameterization in terms of symmetry-adapted collective coordinates are illustrated with multiple examples.
Frank–Kasper structures occur in the metallurgy of alloys, the crystallography of clathrates, in soap froths and in the solution to the weak Kelvin conjecture. By using a new combinatorial enumeration algorithm, 71 new structures have been found.
Agreement factors appropriate for refinements based on the ratios of intensities before and after an external perturbation is applied to a crystal are defined and compared with R factors commonly applied in static structure crystallography.