Jv. Peetz et W. Schattke, NON-MUFFIN-TIN ATOMIC SCATTERING-MATRICES FOR SEMICONDUCTOR LEED-CALCULATIONS, Journal of electron spectroscopy and related phenomena, 68, 1994, pp. 167-173
Non-muffin-tin Potentials for LEED-calculations can be treated by the
integration of the Lippmann-Schwinger equation as described by Nagano
and Tong. We have solved this coupled system of equations numerically
with a code for ordinary differential equations. The general scatterin
g potential is generated by superimposing atomic Clementi-Roetti densi
ties and Coulomb potentials for a cluster of crystal atoms. The exchan
ge potential is modeled as a function of the superimposed electron den
sity. Both, energy-dependent and energy-independent exchange potential
s are investigated. The spherical wave decomposition of the potential
entering the angular momentum representation of the Lippmann-Schwinger
equation is performed with an efficient numerical integration algorit
hm. Spherical wave components of the superposition potential are shown
to emphasize their influence on the LEED-calculation. Scattering ampl
itudes of this potential model are computed and compared with those of
standard muffin-tin phase shifts of GaAs. Especially, surface configu
rations are considered within this procedure.