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The '''dynamical theory of diffraction''' describes the interaction of [[wave]]s with a regular lattice. The wave fields traditionally described are [[X-rays]], [[neutron radiation|neutron]]s or [[electrons]] and the regular lattice, atomic crystal structures or nanometer scaled multi-layers or self arranged systems. In a wider sense, similar treatment is related to the interaction of light with optical band-gap materials or related wave problems in acoustics.▼
[[Image:LaueBraggGeometry.png|thumb|right|250px|Laue and Bragg geometries, top and bottom, as distinguished by the Dynamical theory of diffraction with the Bragg diffracted beam leaving the back or front surface of the crystal, respectively. ([http://liss.freeshell.org/kdl/DissLiss/ Ref.])]]
▲The '''dynamical theory of diffraction''' describes the interaction of [[wave]]s with a regular [[Lattice model (physics)|lattice]]. The wave fields traditionally described are [[X-rays]], [[neutron radiation|neutron]]s or [[electrons]] and the regular lattice
[[Image:RLaueBragg.png|thumb|right|250px|Reflectivities for Laue and Bragg geometries, top and bottom, respectively, as evaluated by the dynamical theory of diffraction for the absorption-less case. The flat top of the peak in Bragg geometry is the so-called Darwin Plateau. ([http://liss.freeshell.org/kdl/DissLiss/ Ref.])]]
==Principle
The dynamical theory of diffraction considers the wave field in the periodic potential of the crystal and takes into account all multiple scattering effects. Unlike the [[Diffraction formalism|kinematic theory of diffraction]] which describes the approximate position of [[Bragg diffraction|Bragg]] or [[X-ray crystallography|Laue diffraction]] peaks in [[reciprocal space]], dynamical theory corrects for refraction, shape and width of the peaks, extinction and interference effects. Graphical representations are described in [[dispersion surfaces]] around reciprocal lattice points which fulfill the boundary conditions at the crystal interface.
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