The CCP4 FFT program does the 90-degree rotation automatically if you
use "DANO=" as the column assignment. The rotation is because anomalous
difference arise from scattering that is 90 degrees out of phase with
"normal" electrons.
-James Holton
MAD Scientist
On 8/29/2014 11:43 AM, Alexander Aleshin wrote:
> Could anyone remind me how to calculate anomalous difference Fourier maps using model-calculated phases? I was doing it by
> (1) calculating PHcalc from a pdb file using Sfall, then
> (2) merging PHcalc with Dano of experimental SFs, then
> (3) calculating a map with Dano and PHcalc using FFT program of CCP4.
>
> Now, I've read Z. Dauter's et all paper http://mcl1.ncifcrf.gov/dauter_pubs/175.pdf, and it said that their anomalous maps were calculated using (delF, PHcalc-90degrees). Why did they use -90 degrees? How does it relay to a (delF, phcalc) map?
>
> Thank you for an advice.
>
> Alex Aleshin
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