Selective adsorption resonances in the scattering of helium atoms from xenon coated graphite: Close-coupling calculations and potential dependence

Accurate close-coupling calculations are carried out for the scattering of helium atoms from a monolayer of Xe on the (0001) face of graphite, using atom-surface potentials based on pairwise additivity and the (known) He-Xe pair potential. Good agreement is obtained with the selective adsorption data of Bracco et al. The potential dependence of the resonance spectrum is explored, and it is found that the data are very sensitive to fine details; two pair potentials which both reproduce the gas phase data well, give significantly different resonance spectra, and the contributions of three-body forces are also shown to be important. The resonance spectra are significantly affected by small changes in the corrugation strength as well as by the laterally averaged potential. The potential dependence becomes even more pronounced as the scattering energy is decreased.