Matthew & Nat, Thanks very much, your answers made me much clear about the map manipulating, as well as usage of Refmac and FFT. Just from my results, I think I agree with Nat that "Sigma" and "Weight" is unnecessary when running FFT based on a Refmac-resulted mtz file, since my "A1.map" is exactly same as FWT of "A.mtz" in Coot.
Again thanks for your help! Zhihong 2011/1/7 Nat Echols <nathaniel.ech...@gmail.com> > On Fri, Jan 7, 2011 at 2:34 PM, Matthew Franklin <mfrank...@nysbc.org>wrote: > >> However, I'm not sure if you're doing the right thing by leaving SIGF >> unassigned. I believe this should be assigned to the experimental error, >> which is usually called 'SIGF' in your mtz file. I don't know if FFT >> actually uses this for anything when it's calculating your map file. I'm >> also not sure what you should use for the weight parameter - perhaps 'FOM'? >> > > FWT,PHWT has the weights already applied to the amplitudes*, so no FOM is > necessary. According to the FFT documentation, the sigmas can be used to > exclude reflections (subject to an additional keyword), but I assume by > default it will just be ignored. > > -Nat > > (* FWT = "2mFo-DFc", where "m" is the FOM.) >
