Structure determination without Fourier inversion. V. A concept based on parameter space

A method of structure determination based on an equal-atom point model is described. The method avoids the phase problem, offers high resolution, works with sparse experimental data and provides all possible (quasi-)homometric solutions.

On symmetry classes of crystal structures

An open-ended classification scheme for crystal structures based on Wyckoff sets and affine normalizer groups is proposed.

Multiresolution of quasicrystal diffraction spectra

The classification of diffraction spectra of aperiodic crystals based on multiresolution analysis is described.

Experimental charge-density study of paracetamol – multipole refinement in the presence of a disordered methyl group

On the basis of high-resolution single-crystal X-ray diffraction data for paracetamol, different approaches (including those based on pseudoatom databases) to modeling of the static experimental electron density in the presence of a dynamically disordered molecular fragment were tested. The electrostatic properties obtained were compared with the results of theoretical single-point periodic calculations.

The OD interpretation of the crystal structure of kettnerite CaBiOFCO₃

The mineral kettnerite, CaBi(OFCO₃), has an order–disorder (OD) structure with a quadratic net built up by more than one kind of layer. Two maximum-degree-of-order (MDO) (1O, 2O) and one non-MDO (2Q) polytypes are derived by stacking of regularly alternating polar OD packets instead of layers. The stacking rule allows the existence of out-of-step, twin and upside-down domains.

Molecular replacement: the probabilistic approach of the program REMO09 and its applications

The method of joint probability distribution functions has been applied to molecular replacement techniques.

Improving the direct-methods sign-unconstrained S-FFT algorithm. XV

The success rate of the direct-methods sign-unconstrained S-FFT algorithm has been improved for density functions with only light scatterers. In addition, a closely related but simpler phase-refinement function is introduced, which can also treat positive and negative density peaks.

Multiplicative congruential generators, their lattice structure, its relation to lattice–sublattice trans­formations and applications in crystallography

An analysis of certain types of multiplicative congruential generators – otherwise known for their application to the sequential generation of pseudo-random numbers – reveals their relation to lattice–sublattice transformations and the coordinate description of crystal structures.

Foundations of Crystallography with Computer Applications

Gjønnes Medal in Electron Crystallography – call for nominations

Prices of IUCr journals