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Rapid progress in solid state spectroscopy and nanoscience has
stimulated interest in detailed understanding of electron scattering
in solids and brought about vigorous activity in developing ab initio
methods for extended systems with broken periodicity.
In this talk, after a review of the state-of-the-art computational approaches to scattering, a novel stationary-states based method will be introduced. With this method the highly advanced methodology of the band structure theory is transferred to -- mathematically speaking -- initial value problems of electronic structure. The cornerstone is a variational embedding technique, which treats on the same footing the infinite host crystal and the scattering region. The history of computational techniques for scattering goes back to early 60s when the main interest was in describing the electron diffraction by surfaces -- LEED. Several examples from this classical area will be presented, supported by recent achievements in refining the experimental technique for very low energies -- VLEED. Special attention will be payed to inelastic effects, which are described phenomenologically by adding an imaginary contribution Vi to the crystal potential. Validation aspects of this theory are discussed using layered chalcogenides NbSe2 and TiTe2 and graphite as examples. Implications of elastic and inelastic scattering for interpretation of photoelectron spectra are discussed. |
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