Hi Phenixbb,

I have a data that indexes in P6122, also P61 and P31. Data analysis in phenix.xtriage says no twinning is suspected according to the L-test.

However, after MR and twin RB refinement, the model improves from P6122 or P61 to P31 5% Rfacs and 0.5 the FOM.

I thought the data might have RPS and twinning not detected with the L-test. So, i ran xtriage to compute the RvsR statistics using the obs_and_calc.mtz file and the results were:

in P61
R_abs_twin observed data : 0.112
R_abs_twin calculated data : 0.047

in P31
R_abs_twin observed data : 0.117
R_abs_twin calculated data : 0.139

"misespecified crystal symmetry", according to Lebedev, Vagin, Murshudov et al 2006, Acta Cryst. D62,83-95.

I would like to know a test that tells me the right symmetry.

I appreciate your help. Thanks,

Gabriela