[phenixbb] isomorphous Fobs-Fobs maps

Schulz, Eike-Christian eike.schulz at mpsd.mpg.de
Mon Jan 20 03:01:05 PST 2020

Dear all, 

we have recently tried to calculate isomorphous difference maps with phenix using the GUI. Unfortunately, we found that the results do _not_ seem to produce results that we would expect of a true difference map. Rather the resulting maps appear to show noise. 

We speculate that this is the result of _not_ scaling the datasets together. 

- Is this correct ?

Applying the "multiscaling method" found in the advanced options changes the result, but it is still inconsistent with what we gain from e.g. the CCP4 procedures. 

Unfortunately, there is no online documentation to this tool. 

- Is there a way to scale the data to a reference before calculating the difference maps? 

- What is the proposed way of using this tool ?

- Are there known bugs in the GUI version that are absent in the command line edition?

With best regards, 


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