Electronic states in diatomic molecules

Abstract

In this Chapter we specialize the concepts given in Chapter 7 for the electronic states by introducing specific forms for the wavefunctions in diatomic molecules. Two main lines of description can be envisaged. In the approach known as molecular orbital (MO) the molecule is built up in a way similar to the aufbau method in atoms, namely by ideally adding electrons to one-electron states. The prototype for this description is the Hydrogen molecule ion H ²₊ . In the valence bond (VB) approach, instead, the molecule results from the interaction of atoms dressed by their electrons. The prototype in this case is the Hydrogen molecule H₂.