THEORY OF FIELD ADSORPTION

Abstract
A first principles theory is formulated to calculate the dispersion (van der Waals) and polarization (induced dipole-dipole) interactions between a solid and an atom in a strong electric field. It is shown that these forces are not strong enough to bind rare gases on field ion tips. We then review a microscopic theory of field adsorption in which the electronic properties of the metal-adsorbate system are calculated within a tight binding cluster approach based on the ASEDMO method with local electric fields taken from self-consistent hellium calculations. Comparison with experiment for helium field adsorption on tungsten is excellent for activation energies, bonding distances and vibrational frequencies. Reference will also be made to the field-induced chemistry of NO on a platinum tip.