Methods of Phase-Angle Determination

Solving the phase problem, that is, obtaining an estimate of the structure factor phase angles that cannot be directly determined from the observed intensity data, is the central task in crystal structure analysis. Three of the more commonly used among the general methods are briefly discussed. 

It has been stated several times that although experimental measurements provide information on the magnitude of the structure factors, the phase-angle information is lost in the observed intensity data. This assertion, however, turns out to be not. completely true, since in the direct methods the phase angles can be estimated 

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