A Variety of Bond Analysis Methods, One Answer? An Investigation of the Element-Oxygen Bond of Hydroxides H XOH.

There is a great variety of bond analysis tools that aim to extract information on the bonding situation from the molecular wavefunction. Because none of these can fully describe bonding in all of its complexity, it is necessary to regard a balanced selection of complementary analysis methods to obtain a reliable chemical conclusion. This is, however, not a feasible approach in most studies because it is a time-consuming procedure.

Visualizing lithium-ion migration pathways in battery materials.

The understanding of lithium-ion migration through the bulk crystal structure is crucial in the search for novel battery materials with improved properties for lithium-ion conduction. In this paper, procrystal calculations are introduced as a fast, intuitive way of mapping possible migration pathways, and the method is applied to a broad range of lithium-containing materials, including the well-known battery cathode materials LiCoO2 , LiMn2 O4 , and LiFePO4 . The outcome is compared with both experimental and theoretical studies, as well as the bond valence site energy approach, and the results show that the method is not only a strong, qualitative visualization tool, but also provides a quantitative measure of electron-density thresholds for migration, which are correlated with theoretically obtained activation energies.

Bonded radii and the contraction of the electron density of the oxygen atom by bonded interactions.

The bonded radii for more than 700 bonded pairs of atoms, comprising more than 50 oxide crystals, extracted from experimental and theoretical electron density distributions, are averaged and compared with the ionic radii for first, second, and third row atoms. At odds with the assumption of a "fixed" ionic radius of 1.40 Å for the oxide anion, the bonded radius for the anion, r(b)(O), decreases systematically from 1.