[phenixbb] Map quality

[Jrh]

Dear Mohamed,
Low completeness in low resolution shells is surely to be avoided.
This should be achievable in monochromatic and white beam (Laue) measuring modes; for the latter, the most challenging, see eg http://dx.doi.org/10.1107/S0909049599006342.

Anyway, from your email, you have this situation; artefacts that may arise and their nature depend on the diffraction resolution that you have and could include false peaks. For true peaks their heights will likely be degraded. Please provide more detail in your query. 

I would also mention that protein crystallography is entrenched in the terminology of electron density map sigmas, whereas chemical crystallography, albeit with an easier challenge of atomic resolution data to hand, present electron density maps in electrons ie an absolute scale, which is most helpful to the viewer.

Best wishes,
John. 

Emeritus Prof John R Helliwell DSc_Physics 



On 15 May 2015, at 17:10, mohamed noor <mohamed.noor34 at gmail.com> wrote:

> Dear all
> 
> Is there a single (or a few) metrics that can be used to quantitatively assess map quality instead of looking at each one in Coot? For example, I want to compare the effect of having low completeness in the low resolution shells.
> 
> Thanks.
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