[phenixbb] Refining low resolution structure

[Humberto Pereira]

Dear all
I was trying to refining a low resolution structure with Phenix.
The crystal belongs to the SG P6122 with one monomer per ASU. The monomer
contains
approximately 270 residues. There isn't any NCS operators.
The crystal diffracts up to 4.0 Angstrons, with good statistics, however I
have only 4204 unique reflections.
I solved the structure by MR by Phaser and the solution was quite
reasonably.
Initially I performed a phenix refining cicle with SA + rigid body, however
the Rs values is very divergent (43 and 59%),
so I decided to use the key xray_data.r_free_flags.ignore_r_free_flags=true
in order to save my precious reflections with and without
SA, and I also use the group_adp., in those cases the R is about 39-40%.
I want a help to decide the best refinement strategies for low resolution
refinement with phenix.
BTW I'm trying to produce some different constructions of the gene,
expecting improve the resolution.

Thanks
Humberto
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