What to read after Molecular Orbitals?

Electron orbitals of molecules, or molecular orbitals (MOs), are ubiquitous in chemistry. It is difficult to imagine modern research in chemistry, materials chemistry, chemical engineering, and related fields—in the broader sense—without the insight that is offered by the description of electronic structure in terms of atomic and molecular orbitals. Despite its importance, orbital theory, and MO theory, in particular, is not always taught rigorously in the chemistry curriculum. This primer is meant to introduce the aspiring chemist to the ideas underlying MO theory, to make it clear what MOs are and what they are not, and to showcase selected qualitative and quantitative applications of MO theory with a strong emphasis on the visualization of orbitals.