Crystallography: Crystal Structures Determination

The article describes (1) the wave-optical principles and the geometric interpretation which explain the diffraction pattern obtained when X-rays strike a crystal; (2) the experimental data which are the Miller indices h and the intensities of the diffracted beams I h ; (3) the Patterson method and the direct methods used to determine a model of the crystal structure for small and medium size molecules; and (4) the completing and refining the model structure until the calculated values and the experimental values are in good agreement.