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<div dir="ltr">On Mon, Sep 8, 2014 at 9:58 AM, CPMAS Chen <span
dir="ltr"><<a moz-do-not-send="true"
href="mailto:cpmasmit@gmail.com" target="_blank">cpmasmit@gmail.com</a>></span>
wrote:<br>
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<div>A difference map is used to identify whether there
is anything not-modeled, say some ligands, ions. Then
when I generate anomalous difference map, I should not
put the ligand(which contains Br) in the model, right?
Or in phenix, after I put the Br-ligand in the model,
I should not see the anomalous difference density at
the site, right?</div>
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<div>An "anomalous difference map" is a map of the anomalous
differences DANO (Fobs(+) - Fobs(-)). �It's independent of
�Fcalc, so it doesn't matter if you put the ligand in or
not.� <br>
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This is not quite an accurate statement. To calculate a Fourier map
one requires amplitudes and phases. (Fobs(+) - Fobs(-)) are the
amplitudes for the anomalous difference map. The phases come from
Fcalc (actually from Fmodel), one way or another.<br>
<br>
Pavel<br>
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