Restraints for atomic displacement parameters of hydrogen atoms in Hirshfeld atom refinement are tested using two polymorphs of the water-rich l-Asp-l-Asp-l-Asp (DDD) crystal structure.

The crystal structure of the mixed tetrahedral–octahedral framework silicate Cs4Ca[Si8O19] has been solved. A topological analysis of the present compound and other interrupted framework silicates is ...

A unique phase transition, twinning and ferroelastic domain structure in [NH3(CH2)2NH3]2[ZnBr4]Br2 is found. The new additional domain structure is observed at the phase transition on heating, which is preserved after cooling to room temperature.

1,2-Bis(3,5-di­methyl-2-thienyl)perfluoro­cyclo­pentene formed its own spherulites by sublimation onto the hydro­philic surfaces of the (0001) planes of α-quartz and sapphire substrates. The formation of different morphologies of these spherulites was attributed to the surface properties of each substrate. Depending on the morphology of the spherulites, hollow rod crystals with cross sections of different sizes and shapes and branching structures were generated on the surfaces of the spherulites.

Tetragonal YxOs4B4 (x = 1.161) is an incommensurate composite of columns of Y atoms in a three-dimensional Os4B4 framework. The structure was refined using the superspace approach.

The structure of Ni3V2O8 was studied using X-ray diffraction at temperatures of 299 and 1323 K. No phase transition at high temperature is observed. The variation in V—O bond length is small as compared with the Ni—O bond due to its high rigidity.

In-situ diffraction measurements reveal that magnesium chloride forms a unique high-pressure phase, a heptahydrate, above 2 GPa. The hydrogen-bonding structure appears to contain orientational disorder.

We show that the interplay of multiple magnetic sublattices in Er2CuMnMn4O12 leads to four magnetic phase transitions characterized by the onset of ferrimagnetic order, spin-reorientation, spin canting, and the polarization of Er ions. While we elucidate numerous features of this complex magnetic system, the exact nature of the low-temperature coupling between erbium and manganese, and the origin of a k = (0, 0, ½) modulation, remain intriguing topics for future studies.

The results of the seventh blind test of crystal structure prediction are presented, focusing on structure ranking methods.

The results of the seventh blind test of crystal structure prediction are presented, focusing on structure generation methods.

Density-functional calculations using numerical atomic orbitals and the exchange-hole dipole moment dispersion model were applied to the energy ranking stage of the seventh crystal structure prediction blind test. This methodology gave successful predictions of the experimentally isolated polymorphs as being low in energy for three of the compounds considered, and for one additional compound upon inclusion of a vibrational free-energy correction.

A design is tested for a polymorph search algorithm relevant for enhanced sampling of crystal structures based on the relation between internal molecular structure variables and corresponding crystal polymorphs as representative of the inherent vapor to crystal transitions that exist in nature. Molecules are represented as extended variables within a thermal reservoir. Unit-cell variables are generated using pseudo-random sampling incorporating a harmonic coupling to extended variables.

The conformational energies and crystal energy landscapes for molecules XXXI and XXXII from the seventh blind test of crystal structure prediction are investigated with a variety of electronic structure methods. Whereas molecule XXXI can be modeled relatively straightforwardly, molecule XXXII proves challenging even for state-of-the-art quantum chemistry techniques.

The crystal structure of calcium atorvastatin trihydrate was redetermined from previously published synchrotron powder diffraction data to give a much-improved agreement with two independent density-functional theory calculations.

Incommensurate phase of potassium guaninate monohydrate is the first example of a modulation in purine derivatives and of a high-pressure incommensurate crystal structure to be solved for an organic compound.

A detailed structural characterization of the δ1-MnZn9.7 phase is presented.

The magnetic structure of the intermetallic compound ErGa as a function of temperature has been determined using a combination of high-resolution neutron powder diffraction and 166Er Mössbauer spectroscopy. ErGa orders as a b-axis ferromagnet at 32 K and undergoes a spin-reorientation at 16 K to yield a canted ferromagnetic structure with the magnetic moments in the bc plane below 16 K.

Introducing the new Section Editor for Acta Cryst. B

Magnetic metal–organic frameworks are candidate materials for investigating two-dimensional phenomena. The magnetic structures of deuterated formate Co(DCOO)2·2D2O has been studied by neutron powder diffraction.

Possible commensurate magnetic structures from neutron powder diffraction data are explored via the Bilbao Crystallographic Server tool k-SUBGROUPSMAG called from within GSAS-II, which allows easy survey of the results and selection of the best magnetic structure model.

The magnetic option of the crystallographic program JANA2020 is a specific tool for solution, analysis, and description of modulated and non-modulated magnetic structures.

An exhaustive search for missing symmetry was performed for 223 076 entries of the ICSD. About 0.65% of the entries can be described with higher symmetry than reported. It is proposed that the information is included in the ICSD.

The mathematical structure, description and classification of magnetic space groups are briefly reviewed, with special emphasis on the new unified (UNI) magnetic space-group symbols.

Magnetic structure study on the noncentrosymmetric magnet Sr2MnSi2O7 using irreducible representation and magnetic space group analyses based on data from neutron diffraction, and magnetometry measurements