Fast analytical evaluation of intermolecular electrostatic interaction energies using the pseudoatom representation of the electron density. III. Application to crystal structures via the Ewald and direct summation methods

The exact potential and multipole moment method for fast and accurate evaluation of the intermolecular electrostatic interaction energies using the pseudoatom-based charge distributions is extended to the calculation of energies in molecular crystal structures. The proposed Ewald and direct summation techniques correctly account for the electron-density penetration effects that in the benchmark systems constitute 24–68% of the total electrostatic interaction energies, and thus cannot be ignored. In agreement with the literature, the Ewald summation method offers a higher precision of the evaluated energies (10⁻⁵ kJ mol⁻¹) and a significantly better computational performance.

A flexible and standalone forward simulation model for laboratory X-ray diffraction contrast tomography

A flexible and standalone forward simulation model has been developed to compute the diffraction projections for laboratory diffraction contrast tomography (LabDCT). The outputs are expected to be of great value for all present users of LabDCT as well as interested new users.

Effect of radiation damage and illumination variability on signal-to-noise ratio in X-ray free-electron laser single-particle imaging

The signal-to-noise ratio and spatial resolution of 3D coherent diffractive imaging are investigated, taking into account the effects of radiation damage to the sample and variability of the incident X-ray intensity. The results are expected to be useful for the design and analysis of X-ray free-electron laser-based imaging experiments.

Similarity isometries of point packings

The notion of similarity isometries is extended to point packings. A characterization for the similarity isometries of point packings is provided and some planar examples are discusssed. Similarity isometries of point packings about points different from the origin are also examined by studying similarity isometries of shifted point packings.

Electron image contrast analysis of mosaicity in rutile nanocrystals using direct electron detection

High-resolution electron microscopy image contrast obtained from a rutile nanocrystal using direct electron detection is quantified and interpreted based on a model of mosaic crystals.

Embedding parallelo­hedra into primitive cubic networks and structural automata description

It is proved that any parallelo­hedron P as well as tiling by P, except the rhombic dodeca­hedron, can be embedded into the 3D pcu net. It is proved that for the rhombic dodeca­hedron, embedding into the 3D pcu net does not exist; however, embedding into the 4D pcu net does exist. For each parallelo­hedron the deterministic finite automaton is developed which models the growth of the crystalline structure with the same combinatorial type as the given parallelo­hedron.

Algorithms for target transformations of lattice basis vectors

Presented here are algorithms for the transformation of lattice basis vectors to a specific target. The algorithms are useful for crystallographic operations in direct and reciprocal spaces alike. The algorithms are demonstrated graphically and numerically.

Indexing of diffraction patterns for determination of crystal orientations

A general approach to indexing of diffraction patterns originating from crystals of known structures is presented. Example algorithms are shown to be applicable to patterns of various types, such as Kikuchi patterns, Kossel patterns or Laue patterns.

Isogonal non-crystallographic periodic graphs based on knotted sodalite cages

Knotted and linked zeolite framework types, based on the sodalite cage (truncated octahedron), are described. Such structures exhibit non-crystallographic symmetry.

Report of the Executive Committee for 2019

Prices of IUCr journals

A Journey into Reciprocal Space: A Crystallographer's Perspective