Negative ions of atoms and diatomic and triatomic molecules

Electron affinity is not determined by solving the Schrödinger equation, but by using a wide range of various types of interactions. In atoms, the bound between the external electron and the integrated electric dipole moment of a neutral atom mainly contributes to electron affinity. In diatomic molecules, electron affinity is defined mainly by the interaction of the external electron and the integrated electric dipole moment of the nearest ion. In a triatomic molecule, the external electron interacts with all integrated dipole moments of the positive core.