An asymptotic approximation of multiple-scattering theory in very-low-energy electron diffraction from a metal surface

An asymptotic approximation of multiple-scattering theory has been used to analyze the intensity of very-low-energy-electron diffraction (VLEED). An a nalytic expression relating the amplitudes of the Bloch waves excited in a crystal (and, hence, the VLEED intensities) to the critical zone points of an infinite crystal has been obtained. The possibilities of the new approac h are compared with a calculation of partial electron-transmission coeffici ents made by the matching method employed conventionally in interpretation of VLEED data. While providing a comparable accuracy, the proposed approach is fairly simple and free of the instabilities inherent in matching-method calculations. The explicit connection of the quantities obtained by this m ethod with the electron dispersion relation for an infinite crystal makes i t promising for analysis of band-structure effects in VLEED and photoemissi on experiments. (C) 1999 American Institute of Physics. [S1063-7834(99)0011 2-4].