Molecular Orbital Theory

Abstract

Abstract This entry outlines the development of theoretical chemistry from its origins to the present highlighting important several theories, techniques, and applications to inorganic chemistry. The field has evolved from the series of postulates that provide the framework for quantum mechanics and which culminated in the Schrödinger equation proposed in 1926. Soon thereafter, the application to chemical systems began. Valence Bond Theory (VBT) and Molecular Orbital (MO) Theory were initial techniques for explaining what for chemists was of critical importance, that is, the nature of the chemical bond in molecules. Each approach is still useful today. Molecular Orbital Theory, however, has enjoyed wider applicability owing to being much more easily handled quantitatively. The explosive growth of digital computing capabilities over the last half‐century can no doubt be traced in part to the intensive number crunching requirements of this type. The article reviews the early work of VBT and MO theory, and the treatment of H 2 , homonuclear, and heteronuclear diatomic molecules in some detail. Sections concerning the important application of mathematical group theory conventions and several techniques that use the self‐consistent field approach define much of the terminology that is commonly used in the field. An up‐to‐date list of references and related articles provided interested readers with much more detail on the techniques and applications in this enormous field.