Validity of the Esbjerg-Nørskov approach to potentials for atom-surface scattering using atomic charge densities

The validity of the Esbjerg-Nørskov assumption with charge densities derived from atomic superposition for helium-surface potentials is examined. For the case of He-Cu(110) a detailed comparision is made between the results of Garcia et al., who find that the assumption works well, and those of Liebsch et al., who find that it does not. The conclusion of Liebsch et al. is shown to be based upon a number of unjustified approximations consisting in using an asymptotic expansion for a lattice sum and a single exponential function for the atomic charge density, which lead to a discrepancy of a factor of four between calculated surface corrugations and those that fitted the experimental data. © 1984.