A theory of reference-plane positions for the substrate-mediated dispersion energies is presented. It is found that two reference-plane positions, $Z_1$ and $Z_2$, are required for the description of the interference and image interactions between two atoms (molecules) in the presence of a surface. Model calculations for $Z_1$, $Z_2$, and other dispersion coefficients are presented for a number of adsorption species on jellium and noble-metal substrates.

• Received 25 February 1985

DOI:https://doi.org/10.1103/PhysRevB.32.868