Abstract
Direct methods in low-energy-photoelectron diffraction can provide only approximate locations of atoms close to the emitter. More detailed structural information has to be extracted from the photoelectron diffraction spectra in the traditional way by comparing the results of multiple-scattering calculations for possible structure models to the experimental data. In this paper we propose a linear-superposition scheme for the wave function which reduces the number of full multiple-scattering calculations needed for the structure optimization drastically. This method allows us to explore a parameter space with a much higher dimension than before, which will improve the reliability of structure determinations considerably.