 |
 |
This does sound like a bug. If one of h,k,l are zero then the reflection is centric in P222 so the truncation will be different I just ran a test on an orthorhombic dataset (P212121) of mine and I do indeed see some strange F=0, sigF>0 reflections, but in Charles Ballard's development version which I've been testing they are OK. I think you'll have to send your data to Charles Ballard ([log in to unmask]) who is working on ctruncate (or Charles I can send you mine if you like) Phil On 10 Feb 2011, at 13:50, Ed Pozharski wrote: > Excellent point and no, these are not missing reflections. SigF is not > zero. Also, if I am not mistaken, missing reflections in the MTZ format > are recorded as NaN. > > Ed. > > On Thu, 2011-02-10 at 12:17 +0000, Eleanor Dodson wrote: >> Are you sure these are real FP=0 or reflections which werent measured >> but have been added for completeness of the h k l list. >> The check is whether the SigF is also 0.00 - in that case they are >> genuinely missing.. >> >> Eleanor >> >> On 02/09/2011 11:34 PM, Ed Pozharski wrote: >>> I observe under some conditions that ctruncate sets some reflections >>> amplitudes to zero. AFAIU, this should not be happening as even >>> negative intensities (there are none in this particular dataset) should >>> produce FP>0 upon truncation. >>> >>> 66 out of ~23000 reflections are zeros after ctruncate is applied. >>> Nothing obvious comes up upon inspecting the corresponding hkl's, except >>> that one and only one is always zero (sg is P21212, so these are not >>> systematic absences). One curious thing is that the I/sigma for these >>> reflections is close to the average I/sigma in the highest resolution >>> range (but it varies and these reflections are in all resolution >>> ranges). >>> >>> A bug? >>> >> > > -- > Edwin Pozharski, PhD, Assistant Professor > University of Maryland, Baltimore > ---------------------------------------------- > When the Way is forgotten duty and justice appear; > Then knowledge and wisdom are born along with hypocrisy. > When harmonious relationships dissolve then respect and devotion arise; > When a nation falls to chaos then loyalty and patriotism are born. > ------------------------------ / Lao Tse /