The functional inorganic materials such as magnetic material, photocatalyst, and ion conductor have been widely developed for the practical use of the energy production system. In order to clarify their functionalities, we performed hybrid-density functional theory (DFT) calculations, based on the molecular orbital method. Onishi chemical bonding rule was established to judge the chemical bonding character in their molecular orbitals. This chapter reviews our studies on clarifying the mechanism of functionalities for the functional inorganic materials.
Keywords
Hybrid DFT;
Molecular orbital;
Magnetism;
Cooperative Jahn–Teller effect;
Onishi chemical bonding rule;
Onishi ionics model;
Lithium ion conduction;
Oxide ion conduction;
Proton conduction;
Bandgap change
Figures and tables from this article:
Figure 2.1. The energy production system by the use of photocatalyst, fuel cell, and lithium ion battery. Solar and waste heat are utilized as energy resource.
Figure 2.4. The schematic pictures of the two types of the superexchange (SE) interactions (a) between manganese's 3dx2 − y2 orbitals via fluorine's 2p orbital and (b) between manganese's 3dx2 − y2 orbitals via fluorine's 2p orbital.
Figure 2.8. The potential energy curve for Cu4F4F12 model, changing the amplitude of the Jahn–Teller crystal distortion in Q2 mode (q) (UB2LYP method).
Figure 2.9. The potential energy curve for Cu4F4F16 model, changing the amplitude of the Jahn–Teller crystal distortion in Q2 mode (q) (UB2LYP method).
Figure 2.10. The shapes and occupation numbers of the singly occupied natural orbital (SONO + 1) for (a) Cu4F4F12 and (b) Cu4F4F16 models, at q = 0.0, 0.15, and 0.5 Å (UB2LYP method).
Figure 2.18. The obtained potential energy curve for La2/3 − xLi3xTiO3 perovskite (LLT), displacing lithium ion along x-axis. d is the lithium ion conduction distance along x-axis (BHHLYP method).
Figure 2.19. The obtained potential energy curve for LaTiO3 perovskite, displacing lithium ion along x-axis. d is the lithium ion conduction distance along x-axis (BHHLYP method).
Figure 2.21. The selected molecular orbitals (MOs) for La2/3 − xLi3xTiO3 perovskite (LLT): (a) d = 0.0 Å and (b) d = 1.935 Å (bottleneck) (BHHLYP method).
Figure 2.23. The obtained potential energy curve for KxBa(1 − x)/2MnF3 perovskite, displacing lithium ion along x-axis. d is the lithium ion conduction distance along x-axis (BHHLYP method).
Figure 2.24. Onishi ionics models I for the oxygen-doped KxBa(1 − x)/2MnF3 perovskite: (a) LiMn8F11O1 model, (b) LiMn8F10O2 (I) model, (c) LiMn8F10O2 (II) model. Lithium ion is displaced along x-axis.
Figure 2.25. The obtained potential energy curves for LiMn8F11O1 model, displacing lithium ion along x-axis. d is the lithium ion conduction distance along x-axis (BHHLYP method).
Figure 2.26. The obtained potential energy curves for LiMn8F10O2 (I) model, displacing lithium ion along x-axis. d is the lithium ion conduction distance along x-axis (BHHLYP method).
Figure 2.27. The obtained potential energy curves for LiMn8F10O2 (II) model, displacing lithium ion along x-axis. d is the lithium ion conduction distance along x-axis (BHHLYP method).
Figure 2.28. The two kinds of the oxide ion conduction paths on AlO2 layer in AMO3-type perovskite. The arrows show the oxide ion paths. In (a) and (b) paths, oxide ion migrates parallel and diagonally to AlOAl bond, respectively.
Figure 2.31. The obtained potential energy curves for Al4O3 model, displacing oxide ion along the diagonal line. d is the oxide ion conduction distance along the diagonal line (BHHLYP method).
Figure 2.32. The obtained potential energy curves for La2Al4O3 model, displacing oxide ion along the diagonal line. d is the oxide ion conduction distance along the diagonal line (BHHLYP method).