Conventional reciprocal space techniques

In any of the reciprocal space methods, which are based exclusively on the use of the observed structure factors, the powder diffraction pattern must be deconvoluted and the integrated intensities of all, or as many as possible, individual Bragg reflections determined with a maximum precision. Only then, Patterson or direct phase angle determination techniques may be employed to create a partial or compete structural model. Theoretical background supporting these two methods was reviewed in section 2.14. 

Currently, Patterson and direct methods are the most frequently employed classical structure solution approaches. The direct phase determination methods are especially successful in solving structures from single crystal data, but their use in powder diffraction increases progressively as the quality of powder data improves, better deconvolution techniques are developed and more precise individual structure factors become available. 

There are many ways to build a model of the crystal structure of a polycrystalline material without first using the intensities of individual Bragg reflections, which are hidden in powder diffraction due to partial or complete overlapping. Most of the direct space approaches are, in effect, trial-and-error methods and they include some or all of the following components  

Obviously, trial-and-error techniques require some, and often extensive, chemical, crystallographic and physical knowledge about a specific class of materials in addition to the availability of a structural database and some experience in structural analysis. 

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