He atom scattering from the graphite (0001) surface: Diffraction peaks, resonance splittings, and isolated resonances

Experimental diffraction peaks and resonance splittings are analyzed with a close coupling scattering calculation to give a consistent He-graphite interaction potential. The interaction is modeled as a sum of effective He-C pair interactions. Previous, more approximate, estimates of bound state matrix elements of the potential were 30% larger than present estimates. The corrugation of the equipotential surface is estimated to be a little smaller than previous "hard wall" estimates. The results are compared with recent ab initio potentials.