Energy expression of the chemical bond between atoms in hydrides and oxides and its application to materials design

Masahiko Morinaga, Hiroshi Yukawa, Hiromi Nakai

    Research output: Chapter in Book/Report/Conference proceedingChapter

    2 Citations (Scopus)

    Abstract

    Using energy density analysis, total energy is partitioned into the atomic energy densities of constituent elements. The atomization energy of each element is then evaluated by subtracting the atomic energy density from the energy of the isolated neutral atom. This recent approach to the energy expression is reviewed of the chemical bond between atoms in hydrides and oxides. For various hydrides, the atomization energies, ΔE H for H atom and ΔE M for metal atom, are evaluated and the ΔE H vs. ΔE M diagram called atomization energy diagram is made. All the hydrides including complex hydrides and metal hydrides can be located on this diagram, although there are significant differences in the nature of the chemical bond among them. Also, for hydrocarbons, CmH, the atomization energy for carbon, ΔE C, increases linearly with the ratio of carbon number to hydrogen number, m/n, while keeping ΔE H constant. It is no longer needed for us to give expression for the C-C bond to be either single, or double or triple bond in CmHn. For metal oxides, the atomization energies, ΔE M for metal atom and ΔE O for O atom, reflect the average structure as well as the local structure. As a result, their values change with the overall density of binary metal oxides. For perovskite-type oxides, the ΔE O value increases by the phase transition from cubic to tetragonal phase, regardless of the tilting-type or the displacement-type transition. One of the applications of this approach is the quantitative evaluation for the catalytic activities of metal oxides (e.g., Nb2O5) on the dehydrogenation reaction of magnesium hydride (MgH2), MgH2 → Mg + H2. The atomization energy concept will provide us a new clue to materials design, for example, catalysts design.

    Original languageEnglish
    Title of host publicationThe DV-X Molecular-Orbital Calculation Method
    PublisherSpringer International Publishing
    Pages183-213
    Number of pages31
    ISBN (Print)9783319111858, 9783319111841
    DOIs
    Publication statusPublished - 2015 Jan 1

    ASJC Scopus subject areas

    • Chemistry(all)
    • Engineering(all)
    • Materials Science(all)

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