Re: [phenixbb] picking Rfree set

2008/1/22, David Garboczi :

...

So, for instance, when addition of a ligand to a P212121 cell (1 mol) changes the symmetry to P21 (almost same cell, but 2 mol), the selection of the Rfree set from the P21 data by phenix.refine will take the higher almost symmetry into account?

Dave

yes, it will.

This is useful for when the data is twinned.

P

But watch out for large deviations from the orthorhombic symmetry. The tolerance is controlled by the r_free_flags.lattice_symmetry_max_delta parameter. The default is pretty generous (5 degrees) but you should check that that's enough for your case. You can use the iotbx.lattice_symmetry command with --delta=5 to verify that you get the orthorhombic symmetry starting from your monoclinic cell. Ralf