The Interaction Between a Molecule and a Metal Surface

The interaction between a molecule and a metal surface is discussed from the point of view of the perturbation theory. The interaction energy is found to be inversely proportional to the distance, $R$, between metal and molecule if the electron degeneracy in the metal is not taken into account and to $R^{-2\mathrm{}}logR$ if this degeneracy is taken into account. The application of the perturbation theory as given here is limited to values of $R$ of the order of magnitude of the Bohr radius because of the neglect of the electron-electron interaction.