Key principles of X-ray diffraction

If an X-ray beam could be reflected from every possible stack of hkHattice planes that bisect the unit cell such that every reflection satisfied the Bragg law, then the total ordered pattern of X-ray scattering would represent the complete diffraction pattern. In reality, this is not possible to achieve without rotating the crystal in the path of the X-ray beam and/or using a 

Another view of X-ray diffraction has grown out of the Bragg law, and this is the consideration of the diffraction phenomenon in terms of vectors. This consideration has led to the following equation, which encapsulates the entire relationship between unit cell electron density and the X-ray diffraction pattern  

In practice, only P hkl) can be solved completely beginning with a Patterson function, P(mvw), that is almost identical in form to Equation (6.5) but for the absence of phase angles (angles are all set to zero) and the involvement of an J (hfc/ ) term, as shown in the following equation  

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