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Note: in this text F_{H} designates the structure factor corrected for thermal motion and brought to an absolute scale; generally this is done using a Wilson plot. Since the scattering factor of any atom decreases for larger reflection angle , and the expected intensity of a reflection is given by
(1) |
(2) |
The structure-factor expression in terms of the normalized structure factor is then:
(3) |
(4) |
In order to find the maximum value of |E|, let us consider an equal atom structure for which the structure factor (4) further reduces to
(5) |
The unitary structure factor U was used extensively in the early literature on Direct Methods:
(6) |
|E_{H}|^{2} = N|U_{H}|^{2}. | (7) |
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