He4 interaction with and scattering from graphite

Calculations are presented of diffraction intensities for the scattering of He4 from graphite basal plane. The potential employed is a corrugated hard wall plus attraction. The choice of parameters is made by modeling a more realistic potential derived by pairwise summation of He-C interactions. These pair interactions are taken to be of either Yukawa-6 or Lennard-Jones 6-12 form, with coefficients derived by comparison with experimental data of Boato et al. (differing in value from those used traditionally). The computed linewidths, positions, and splittings are in good overall agreement with the scattering results. The role of inelastic effects is explored using a complex potential with a constant imaginary part for small atom-surface separation.