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Dear Dipankar, Molrep Rfactors around 50% with a model with 100% identity means that something went wrong and you did not find the solution. To find the problem, I would proceed as follows: 1) check the processing of the data and the space group: Are the statistics of the processing ok? Did you let the processing software find the space group, or did you specify it? The true space group maybe different from what you think. You may also process in P1 and let pointless figure out the space group. 2) check that you used the correct search model. It maybe trivial but if you mixed up pdb files, you will never find a solution. 3) run Molrep of Phaser with the option to test all possible spacegroups for your crystal system. During processing it is not always possible to reliable distuinguish e.g. between P212121, P21212, P2221 etc. The only way to find out is to systematically try all possibilities. All molecular replacement programs do have an option for this. 4) It may also be to you searched for too many or too few molecules. Do separate searches for 1 to as many molecules as fit in the asymmetric unit. It is not common but crystals exist with only 30% solvent or as much as 70% solvent. 5) Finally, try to find an experienced crystallographer to help you. Again, your problem is not with the refinement, but with the molecular replacement. Good luck! Herma ________________________________ From: CCP4 bulletin board [mailto:[log in to unmask]] On Behalf Of Dipankar Manna Sent: Wednesday, March 14, 2012 10:26 AM To: [log in to unmask] Subject: [ccp4bb] How to reduce R factor Dear Crystallographers, Can anybody guide me how to reduce R-factor, means which are the basic parameters I have to look for to reduce the R-factor during refinement. I am newly learning the refinement. After running molrep R-factor is around 53% (100% identity), after rigid body refinement its showing around 49% and after restrained refinement its showing around 47%. Highest resolution is 2.5A. Regards Dipankar ________________________________ This e-mail and any files transmitted with it are for the sole use of the intended recipient(s) and may contain confidential and privileged information.If you are not the intended recipient, please contact the sender by reply e-mail and destroy all copies of the original message.Any unauthorized review, use, disclosure, dissemination, forwarding,printing or copying of this email or any action taken in reliance on this e-mail is strictly prohibited and may be unlawful. Visit us at http://www.aurigene.com