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

Masahiko Morinaga*, Hiroshi Yukawa, Hiromi Nakai

*この研究の対応する著者

研究成果: Chapter

2 被引用数 (Scopus)

抄録

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 <100> 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.

本文言語English
ホスト出版物のタイトルThe DV-X Molecular-Orbital Calculation Method
出版社Springer International Publishing
ページ183-213
ページ数31
ISBN(電子版)9783319111858
ISBN(印刷版)9783319111841
DOI
出版ステータスPublished - 2015 1 1

ASJC Scopus subject areas

  • 化学 (全般)
  • 工学(全般)
  • 材料科学(全般)

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