Learning from approximate periodic symmetry in organic P1 structures

A short commentary is given on a recent paper by Carolyn Pratt Brock [Acta Cryst. B78, 576–588] which discusses the occurrences of approximate symmetries in space group P1.

Engineering the band gap and optical properties of a two-dimensional molybdenum carbon fluoride MXene

Using first-principles density functional theory, the electronic and optical properties of monolayer and multilayer nanosheets of molybdenum carbon fluoride (Mo₂CF₂), a two-dimensional (2D) transition-metal carbide MXene, were investigated. The unique behavior of its optical properties along with the ability to control its electronic and optical properties enhances the potential of 2D Mo₂CF₂ for various applications in the fields of electronics and energy storage.

Evolution of microstructure and crystallographic texture throughout the rolling process of AA3104

The crystallographic texture evolution in 3xxx Al alloys in different processing routes is presented and compared to the anisotropic effects occurring during deep drawing. The earing phenomena in Al alloys are correlated to the produced texture and therefore their understanding is crucial in order to highlight the importance of texture control throughout the thermomechanical process.

One-dimensional diffuse scattering of 1,3-di(tert-butyl)cyclo­pentadienyl pentaphosphaferrocene modelled with closed-form expressions

The diffuse scattering of 1,3-di(tert-butyl)cyclopentadienyl pentaphosphaferrocene (Cp′′FeP₅) is modelled with closed-form expressions derived from a growth model with the range of interactions (reichweite) s = 2.

Heterocyclic 1,3-diazepine-based thio­nes and selones as versatile halogen-bond acceptors

Utilizing the N-heterocyclic chalcogenones hexa­hydro-1,3-bis­(2,4,6-tri­methyl­phenyl)-2H-1,3-diazepine-2-thione (SDiazMesS) and hexa­hydro-1,3-bis­(2,4,6-tri­methyl­phenyl)-2H-1,3-diazepine-2-selone (SDiazMesSe) as halogen-bond acceptors, 24 new cocrystals were prepared. The solid-state structures of the parent molecules were also determined, along with those of their aceto­nitrile solvates.

The effect of hydro­static compression on the crystal structure of glycinium phosphite

The effect of hydro­static compression on the crystal structure of glycinium phosphite is explored by single-crystal X-ray diffraction and DFT calculations and discussed in relation to a possible ferroelectric phase transition.

Lattice defects in quinacridone

Various lattice defects in the α^I-phase of quinacridone (C₂₀H₁₂N₂O₂) were simulated using lattice-energy minimizations, including vacancies, stacking faults, screw and edge dislocations, twinning and orientational faults. Twinning and orientational faults of entire chains were calculated to occur most frequently.

The potential of dispersion-corrected density functional theory calculations for distinguishing between salts and cocrystals

The limits of DFT calculations for distinguishing between salt and cocrystal are shown. Issues related to false salt identification mentioned in other articles are confirmed. A workflow was developed which, by the use of computational methods, allows the confirmation of salt, cocrystal and intermediate salt-cocrystal phases as well as identifying structures for which the confirmation cannot be made and further analysis is required.

Structures of Ca₅(VO₄)₃Cl and Ca_4.78(1)Na_0.22(PO₄)₃Cl_0.78: positions of channel anions and repulsion on the anion in apatite-type compounds

Apatite-type compounds Ca₅(VO₄)₃Cl and Ca_4.78 (1)Na_0.22(PO₄)₃Cl_0.78 were synthesized and their structures examined with single-crystal X-ray diffraction. The position of the channel anion in Ca₅(VO₄)₃Cl was split into two. Dynamic disordering of Cl⁻ between these two positions was suggested from their highly anisotropic displacements (dominant in 〈001〉) with saddle-shaped electron density distribution through the regular Ca2 triangle.