[ccp4bb]: fft problem

[Jianghai Zhu <zhu5@purdue.edu>]

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Dear all,

I am trying to use fft to calculate an anomalous difference map in R32 
spacegroup. I calculated the map for the whole unit cell and I used peakmax 
to find the peaks. I have three heavy atoms in the asymmetric units. So for 
each heavy atom, I should have 18 sites in the map with exactly the same 
height. But the results I got are either more or less than 18, depends on 
what programs I am using, fft or fftbig. 

Since fft cannot handle R32, it actually use p1 to do the job. I used CAD to 
expand my data to p1 and then use fft to calculate the map under p1, but the 
peaks I found are totally different from those peaks I got from fft under R32 
without manually data expanding. 

Can anybody give me some suggestions?

Thanks.

Jianghai

-- 
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Jianghai Zhu
Biochemistry & Molecular Biology
Purdue University
Lilly Hall, B203
Tel:  765-4949247 (O)
       765-4633336 (H)
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