Figure 5: Dependence of δiso(H+) and δiso(H−) on the characteristic parameters of proton local environment. | Nature Communications

Figure 5: Dependence of δiso(H+) and δiso(H−) on the characteristic parameters of proton local environment.

From: Hydride ions in oxide hosts hidden by hydroxide ions

Figure 5

Model systems are: (a) OH− ion sandwiched between two Mg2O2 clusters and forming a hydrogen bond with another Mg2O2 cluster, (b) an H− ion at the anion site in the bulk of a rock-salt ionic crystal, such as MgO or LiH. (c) Electron density along the O–H bond of an OH− ion for several values of dO–H…O plotted against distance from O atom of the OH− ion. Black to blue lines correspond to dO–H…O values of 220, 240, 260, 280, 300, 340 and 400 pm. (d) Electron density along the Mg–H bond of an H− ion in MgO for several values of dM–H. Black to blue lines correspond to dM–H values of 200, 220, 240, 260, 280 and 300 pm. (e) Dependences of δiso(H+) and δiso(H−) on dO–H…O (circles) and dM–H (triangles for M=Mg and squares for M=Li), respectively. Light-green arrows in (c) and (d) indicate increasing volume associated with hydrogen species, while grey arrows indicate the corresponding change of the charge density magnitude at the hydrogen site.

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