INTERACTIONS BETWEEN ADATOMS ON METALS AND THEIR EFFECTS ON HEAT OF ADSORPTION AT LOW SURFACE COVERAGE

The indirect interaction between adatoms on a metal surface which arises because the adatoms share the itinerant electrons of the system will lead to a dependence of the heat of adsorption on the surface coverage. This dependence is investigated by treating a simple model Hamiltonian in the ordinary Hartree-Fock approximation. The indirect interaction has many-body character, but this does not affect the initial slope of the curve of heat versus coverage. Estimates of this slope for both thermally equilibriated, and randomly distributed adatoms on tungsten indicate that for the former, but not for the latter, an initial rise in the heat with coverage is possible on the (110) plane if the dipole moment of the surface bond is not too large. © 1969.