[phenixbb] Refining f'/f"?

Bryan W. Lepore Bryan.Lepore at umassmed.edu
Thu May 7 12:26:54 PDT 2009

On Thu, 7 May 2009, Nathaniel Echols wrote:
>  I think it's very common for these to have negative difference map 
> peaks, because they'll undergo radiation damage very quickly relative to 
> the rest of the protein.

my understanding is that if there was significant absorption, and if the 
model scattering is uncorrected for f' - which is in-phase with normal 
scattering f for that atom - Fc will overestimate Fo, thus, Fo-Fc will be 

the f'' component will be -(pi/2) out of phase with the normal f, and - 
here is what i don't get - shift the F so its out of phase.  but i don't 
intutitvely understand how that affects the Fo-Fc map.


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