Any signs of twinning? Check also the correctness of your space group: probably you could index In a lower symmetry Laue group with a slight increased distorsion index. Fulvio ----Messaggio Originale---- Da: Benoît Masquida Inviato: 29/05/2013, 14:53 A: PHENIX user mailing list Oggetto: [phenixbb] problem refining RNA structure at 4Å resolution Dear phenix users, I solved using MR a low resolution RNA structure taking data up to 4.3Å and a model of a structure with slight differences. However, when I try to refine, Rwork decreases quickly (start 47, final 32 but Rfree remains high (start 48, final 44). The data are pretty good up to 4.0 with I/sigma above 1. The map doesn't point clearly to wrong regions of the model. What can I try to improve the maps and build the correct model? Thanks in advance. Benoit _______________________________________________ phenixbb mailing list [email protected] http://phenix-online.org/mailman/listinfo/phenixbb