The canonical exchange energy modulation parameters in molecular MTXα calculations. Some first row homonuclear diatomic molecules

The canonical MTXα scheme which uses the parameters α_I = $\text{2}\text{3}$ for all atoms, and α_II = 1 for all molecules is developed and applied to the calculation of the potential energy curves and ionization potentials for the ground electronic states of B₂, C₂, N₂, O₂ and F₂.     

Crystal structure of naturally occurring mercury(II) amidonitrate

A naturally-occurring mercuroammonium compound from Pitkin County, Colorado, is shown to be the natural analog of synthetic HgNH₂NO₃. The crystals are isometric, P4₁32 or P4₃32, with a = 10.254(1)Å and twelve formula weights per cell. Using 437 symmetry-independent reflections, the crystal structure was partially determined and refined to a residual of 0.090. The positions of the Hg atoms and the N and O atoms of the nitrate group were determined, but the amide ion could not be located, probably due to positional disorder. The structure contains mercury atoms arranged in equilateral triangles 3.421(1) Å on a side. These triangles are linked through shared vertices into helical chains wound around the fourfold screw axes. Similar triangular units occur in other inorganic Hg(II) compounds. The distortion of the nitrate ion from trigonal planar symmetry is also discussed.     

On the Origin of the Non-Arrhenius Na-ion Conductivity in Na3OBr

The sodium-rich antiperovskites (NaRAPs) with composition Na₃OB (B=Br, Cl, I, BH₄, etc.) are a family of materials that has recently attracted great interest for application as solid electrolytes in sodium metal batteries. Non-Arrhenius ionic conductivities have been reported for these materials, the origin of which is poorly understood. In this work, we combined temperature-resolved bulk and local characterisation methods to gain an insight into the origin of this unusual behaviour using Na₃OBr as a model system. We first excluded crystallographic disorder on the anion sites as the cause of the change in activation energy; then identified the presence of a poorly crystalline impurities, not detectable by XRD, and elucidated their effect on ionic conductivity. These findings improve understanding of the processing-structure-properties relationships pertaining to NaRAPs and highlight the need to determine these relationships in other materials systems, which will accelerate the development of high-performance solid electrolytes.