Long-range interaction between rare-gas atoms or simple molecules and the surfaces of LiF, CaF2, sapphire, and BN

An atom or a molecule approaching a surface experiences an attractive potential given by V(z)-C3/z3. We have computed C3 for rare-gas atoms and simple molecules interacting with surfaces of various insulators. Our calculation utilizes (frequency-dependent) atomic polarizabilities and dynamic dielectric functions obtained from optical data. A comparison is made with C3 values deduced from multilayer adsorption data on CaF2. We show that a simple formula can be used to evaluate C3 that utilizes readily available constants. We have also computed the long-range surface-mediated interaction between two adsorbed atoms on a surface. We then present a discussion on adsorption of adatoms on hexagonal BN as compared to that on a graphite substrate.