The need for a new generation of substructure searching software

Current state-of-the-art substructure searching in the Cambridge Structural Database is discussed and proposals are made for substructure searching that would encompass both topological searches and searches for molecular fragments that could be used to enable easier searching for complex molecules.

N-Representable one-electron reduced density matrices reconstruction at non-zero temperatures

This article retraces different methods that have been explored to account for the atomic thermal motion in the reconstruction of N-representable one-electron reduced density matrices from experimental X-ray structure factors and directional Compton profiles.

X-ray restrained extremely localized molecular orbitals for the embedding of quantum mechanical calculations

X-ray restrained extremely localized molecular orbitals (XR-ELMOs) were used in QM/ELMO calculations of excited states to describe the environment of a chromophore. It is demonstrated that the XR-ELMOs can be profitably used for this purpose, also confirming the capability of the X-ray restrained wavefunction approach in capturing environmental effects on the electron density.

Spin-resolved charge density and wavefunction refinements using MOLLYNX: a review

This article describes the joint refinement program MOLLYNX dedicated to spin-resolved electron density distribution. Multipole and atomic orbital models are described and applications for organic and inorganic magnetic materials are discussed.

The influence of refinement strategies on the wavefunctions derived from an experiment

The influence of data manipulation on X-ray wavefunction refinement is analysed. While the Hirshfeld atom refinement always reaches the same results, X-ray constrained wavefunction fitting is extremely sensitive to crystallographic data manipulation as a consequence of the variability of the experimental uncertainties for different resolution intervals.

X-ray diffraction study of the atomic interactions, anharmonic displacements and inner-crystal field in orthorhombic KNbO₃

The chemical bonding and anharmonicity of atomic vibrations in stoichiometric single crystals of orthorhombic ferroelectric KNbO₃ have been studied by the precise X-ray diffraction method. The features of the electron density in the cation and anion substructures, and their roles in the formation of spontaneous polarization are established.

Ferromagnetoelectric phases of hexaferrites: a group-theoretical analysis

A symmetry-guided approach for designing and tailoring magnetoelectric and multiferroic M-, W- and Z-type hexaferrites is proposed.

A general model for the crystal structure of orthorhombic martensite in Ti alloys

A unified approach is developed to describe the crystal structure of orthorhombic martensite (α′′) independent of chemical composition. It emerges that a large fraction of structural configurations along the b.c.c.–Cmcm–h.c.p. transformation path is not observed in quenched Ti alloys.

Understanding distortions of inorganic sub­structures in chlor­ido­bis­muthates(III)

Four chlor­ido­bis­mu­thates(III) showing different anionic substructures, two with N,N-di­methyl­ethane-1,2-di­ammonium and the other two with N,N,N′,N′-tetra­methyl­guanidinium organic cations, were studied with respect to the formation of specific inorganic substructures and, in particular, the factors responsible for their distortions from ideal octahedral geometry. The investigations of the poly­hedral distortions were supported by an analysis of data retrieved from the Cambridge Structural Database.

Structure of boehmite-derived γ-alumina and its transformation mechanism revealed by electron crystallography

The crystal structure of γ-alumina was revealed by electron crystallography and its transformation mechanism from boehmite is proposed.

Accurate H-atom parameters for the two polymorphs of L-histi­dine at 5, 105 and 295 K

Single-crystal neutron and X-ray diffraction data for the orthorhombic and monoclinic polymorphs of the amino acid L-histi­dine have been collected at 5, 105 and 295 K. The neutron structural models are com­pared with those refined with the new Hirshfeld atom refinement method implemented in NoSpherA2.

Crystal structure and magnetic properties of the layered hybrid organic–inorganic compounds M₂(OH)₂(C₁₄H₈O₄) (M = Mn, Fe)

M₂(OH)₂(bpdc) (bpdc = bi­phenyl di­carboxyl­ate, C₁₄H₈O₄) is an uncompensated antiferromagnet crystallizing in space group P1, whereas the isoreticular Mn₂(OH)₂(bdc) (bdc = benzene di­carboxyl­ate, C₈H₄O₄) crystallizing in C2/m is a compensated antiferromagnet.

A new guaninate hydrate K⁺·C₅H₄N₅O⁻·H₂O: crystal structure from 100 to 300 K in a comparison with 2Na⁺·C₅H₃N₅O²⁻·7H₂O

A new guanine salt hydrate, K⁺·C₅H₄N₅O⁻·H₂O, was characterized by single-crystal X-ray diffraction in the temperature range 100 K–300 K.

Preparation of polyethylene oxide single crystals via liquid gating technology and morphology design strategy

A novel strategy is provided for the preparation of polyethylene oxide (PEO) single crystals, combining liquid casting technology and the self-seeding method. The resulting PEO single crystals exhibit an ordered single-crystal structure.

Crystal and magnetic structures of R₂Ni_1.78In compounds (R = Tb, Ho, Er and Tm)

Magnetic structures in R₂Ni_1.78In (R = Ho, Er and Tm) are determined from powder neutron diffraction data with the support of symmetry analysis. The results of DC magnetometric measurements for Tm₂Ni_1.78In are also reported.

Anion substitution and influence of sulfur on the crystal structures, phase transitions, and electronic properties of mixed TiO₂/TiS₂ compounds

A theoretical investigation of structural and electronic properties of TiO_1–xS_x (x = 0, 0.25, 0.50, 0.75 and 1) solid solutions is presented. Calculations are performed at the ab initio level using density functional theory and the Crystal17 software.

Self-assembling of three rare structurally various homomultinuclear Cu^II complexes derived from a bis­(salamo)-based multioxime ligand

Three rare structurally different homometal multinuclear Cu^II bis­(salamo)-based complexes have been successfully synthesized and structurally characterized. Due to the existence of different solvent molecules and counter anions, the structures and interactions of the three complexes are influenced.

Analytical description of nanowires. I. Regular cross sections for zincblende and diamond structures. Corrigendum

In the paper by König & Smith [Acta Cryst. (2019), B75, 788–802], several equations had minor errors in their coefficients defining characteristic lengths and area of zinc-blende nanowire cross sections, thereby deviating from the exact analytical solution by 1.4 ± 0.8 %.