Re: [ccp4bb] Absorption correction in small molecule crystals

2015-03-04 Thread Finke Aaron (PSI)
Dear all, Thanks for the insights. Cheers, Aaron -- Dr. Aaron Finke Postdoctoral Fellow Swiss Light Source WSLA/217 CH-5232 Villigen-PSI phone: +41 56 310 5652 e-mail: aaron.fi...@psi.ch On Mar 3, 2015, at 18:43, George Sheldrick wrote: > Dear Finke, >

Re: [ccp4bb] Absorption correction in small molecule crystals

2015-03-03 Thread George Sheldrick
Dear Finke, SADABS and similar programs work best when given scans about several axes relative to the crystal. Scanning about a single axis can do more harm than good especially if the symmetry is low. SADABS can also do a face-indexed numerical absorption correction too, but this assumes that

[ccp4bb] Absorption correction in small molecule crystals

2015-03-03 Thread Finke Aaron (PSI)
Dear comrades, This is slightly off-topic but there are enough experts here to warrant asking. Here at SLS I occasionally get asked to collect small molecule data on the synchrotron. By convention, post-refinement corrections for X-ray absorption by the crystal are required for publication in A

[ccp4bb] absorption correction during anomalous scaling

2014-04-20 Thread Monica Mittal
Hi, everyone I have a question about HKL2000. During scaling, there is a check option call absorption correction. I processed the data with and without it checked. With absorption correction checked, my chisq. anomalous is more than 2.0 for all resolution shells. When I leave it out, chisq. anomal

Re: [ccp4bb] Absorption Correction

2009-09-01 Thread James Holton
Lots of things change with wavelength and absorption is one of the more prominent ones, but in the end its all just path lengths and Beer's law, so the exact answer depends on the geometry. For example, if you are talking about a flat detector 200 mm from the crystal, then 2 A spots with 1 A

[ccp4bb] Absorption Correction

2009-09-01 Thread James Stroud
Hello All, I did diffraction with the exact same sample at 1 Å and at 1.54 Å and noticed that the higher-resolution data from the 1 Å source is more intense relative to the 1.54 Å source after normalizing cumulative intensity between the two data sets. Is this effect from air absorption o

[ccp4bb] Absorption correction in HKL2000

2009-04-16 Thread Zheng Zhou
Hi, everyone I have a question about HKL2000 too. During scaling, there is a check option call absorption correction. I processed the data with and without it checked. With absorption correction checked, my rejection file is only 0.4%. When I leave it out, the rejection file is 0.8%. I read throu