The role of an energy-dependent inner potential in quantitative low-energyelectron diffraction

Recent apparent discrepancies between results from low-energy electron and X-ray diffraction concerning a reduced in-plane lattice parameter of Cu(100 ) are resolved in favour of an uncontracted surface. We show that neglectin g the energy dependence of the inner potential in the electron intensity an alysis simulates reduced structural parameters when a precision level of ab out 0.01 Angstrom is reached. As today this level is frequently claimed, ou r finding is of general relevance, in particular when the in-plane lattice parameter is not precisely known, as in epitaxial growth, for example. (C) 2000 Elsevier Science B.V. All rights reserved.