# MAD phasing - part 2

### Karle/Hendrickson equations

The complete structure factor for an individual reflection *h* at
wavelength is:

Note that the normal scattering component of the anomalous scattering
atoms appears in more than one place in this equation; it is included
in ^{0}F_{T}(*h*), in ^{0}F_{Ak}(*h*),
and in the explicit terms _{k}.
The reason for this is that we want to reformulate things in terms of the ratio
of
and to
.

### MAD phasing of Karle [1980] as formulated by Hendrickson [1985]

Now we will consider the simplest case, with only one type of anomalous
scattering atom, and express the magnitude of measured intensity
**|(h)|**
in terms of its components:

where

**
Note the important fact that all of the wavelength-dependence has been
collected into the coefficients
a(),
b(), and
c().
**

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Ethan A Merritt ©1995-2001/ merritt@u.washington.edu /
Biomolecular Structure Center at UW