Chapter 12 New Expression of the Chemical Bond in Hydrides Using Atomization Energies

Atomization energy diagram is proposed for analyzing the chemical bond in the hydrides including perovskite-type hydrides, metal hydrides and complex hydrides. The atomization energies of hydrogen and metal atoms in them are evaluated theoretically by the energy density analysis (EDA) of the total energy, and used for the construction of the atomization energy diagram. Every hydride can be located on such an energy scaled diagram, although there are significant differences in the nature of the chemical bond among various hydrides. When the hydrides have a resemblance in the chemical bond, their locations are close to each other on the diagram. This diagram reflects characteristics of the chemical bond, since the atomization energy of hydrogen changes largely with the covalent or ionic interactions. Also, the roles of constituent elements in the hydrides are understood well with the aid of the atomization energy diagram.