Re: [phenixbb] Twinned data with Phaser

I can answer my own question about the effect of twinning on CC(1/2): here is a graph of CC(1/2) vs. resolution, estimated by the method of Assmann et al, see below. CC1/2tw are the values for artificially twinned data. There’s not much difference Phil Ref: Greta Assmann, Wolfgang Brehm, & Kay Diederichs, "Identification of rogue datasets in serial crystallography", J.Appl.Cryst, 49, 1021-1028 (2016)

On 25 May 2021, at 10:14, Phil Evans wrote:

I wonder whether our common metrics for assessing resolution are more optimistic for twinned data compared to untwinned - has anyone investigated that? Fewer weak reflections will reduce any sort of R-factor, but i’m not sure of its effect on CC(1/2)

There is always the question of what we mean by “the resolution of the data"

Phil

...

On 24 May 2021, at 22:45, Thomas, Leonard M. wrote:

Hello,

I have been working on a structure for a very long while. We have a number of data sets with the good ones mostly around the 3.1-3.2 A range. I do have a determination of the structure but would like to see if I can get the structure determined with a slightly higher resolution data set at around 2.7 A. Problem is the 2.7 data is twinned. Are there settings in Phaser to handle twinned data or is the twinning only handled during refinement?

Thank you for any advice, outside of forgetting about the twinned data.

Len

Leonard Thomas, Ph.D. Macromolecular Crystallography Laboratory Oklahoma COBRE in Structural Biology Price Family Foundation Institute of Structural Biology University of Oklahoma Department of Chemistry and Biochemistry Stephenson Life Sciences Research Center 101 Stephenson Parkway Norman, OK 73019-5251 Office: (405)325-1126 [email protected] http://www.ou.edu/structuralbiology/cobre-core-facilities/mcl

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