Ian is, as always, absolutely right. The only comment/correction I have
is that Hailang was apparently referring to severely incomplete model,
for which the poor phases will dominate the mFo map. Under such
circumstances, even 2fo-fc map will not correctly reflect the actual
relative contribution
On Wed, Sep 1, 2010 at 4:26 AM, Ed Pozharski wrote:
> The
> reason you see the missing region in (2mFo-DFc) map is because it is
> effectively the sum of model map (mFo) which shows you the parts of the
> model you have already placed and difference map (mFo-DFc) which shows
> you the regions whic
Remember you need to look at half the contour height in a mFo map
compared to a 2mFo-DFc map - the same domain should show up but at a
lower relative contour level in both maps.
REFMAC calculates a similar WCNG and you can look at the graph of m
after refinement to see how close it is to 1. If
If I understand correctly, the only difference between "mFo" and "Fo"
map will be weighting in different resolution shells according to
figure-of-merit. While this will presumably downweigh the less reliable
resolution shells, it will hardly make up for the heavy model bias. The
reason you see th
Actually I cut a small domain from the well-defined structure (just for a
test). The missing part showed in 2mFo-DFc map but not in both mFo and Fo
maps, and the mFo and Fo maps are so close so that I wonder whether figure
of merit generated by SIGMAA helps or not in this situation...
Best Regards
On Tue, 2010-08-31 at 13:15 -0400, Hailiang Zhang wrote:
> Is the difference
> between mFo and Fo maps supposed to be very small?
For an essentially correct model, yes. The major advantage of (2mFo-DFc)
maps is suppression of model bias, so if you don't see much difference
then your model is very
Hi Hailiang,
m is typically determined per resolution bin using test reflections and
it can range from 0 to 1, so the difference between corresponding mFo
and Fo can range accordingly.
You can read more on this, for example:
Acta Cryst. A42 (1986) 140-149.
Acta Cryst. (1995). A51, 880-887.
J
Hi,
I want to see how the mFo maps (NOT 2mFo-DFc) compare against Fo maps. In
the SIGMAA documentation, it says WCMB is the figure of merit; however, I
opened in coot with "FP PHIC WCMB" combination, and for lots of systems, I
didn't see too much difference against "FP PHIC" maps. Is the differenc
