Re: [phenixbb] poor phasing

R vs R statistic: R_abs_twin = <|I1-I2|>/<|I1+I2|> Lebedev, Vagin, Murshudov. Acta Cryst. (2006). D62, 83-95 R_abs_twin observed data : 0.012 R_abs_twin calculated data : 0.300 Is R_abs_twin the same thing as Robs_twin in Lebedev, Vagin, Murshudov. Acta Cryst. (2006). D62, 83-95 ? And I guess I have rotational pseudo symmetry with Rcalctwin < 1/2. Interestingly when I run xtriage when the data is scaled into P 41 21 2 I get the following stats R vs R statistic: R_abs_twin = <|I1-I2|>/<|I1+I2|> Lebedev, Vagin, Murshudov. Acta Cryst. (2006). D62, 83-95 R_abs_twin observed data : 0.012 R_abs_twin calculated data : 0.521 since r_abs_twin or r_obs_twin ~= 0, that's an indicator for perfect twinning. FR On Apr 27, 2009, at 8:58 AM, Peter Zwart wrote:

Try supplying a pdb file

phenix.xtriage mydata.sca reference.structure.file=mymodel.pdb

for the RvsR analyses.

P

2009/4/27 Francis E Reyes :

...

Interesting. I checked my data in P4 with xtriage and yet L-test comes at a respectable 0.948. How does one assess pseudo rotational symmetry in the refined structure?

Thanks

FR

On Apr 27, 2009, at 8:48 AM, Peter Zwart wrote:

...

...

I have yet to find a twinning test that can assess perfect twinning.

I think you mean perfect twinning in the presence of pseudo rotational symmetry. Without the latter part, The L-test works very well.

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