It would seem that you have a large model bias. Rule of thumb is to keep R/Rfree within 5% of each other. If you find that the numbers are separating during refinement you need to reduce the weighting factor (dont use automatic) during refinement. What is your overall redundancy? Higher redundancies (>7 or so) do tend to increase overall R/Rfree. Dont worry so much about getting the R-factor down as supposed to keeping it close to the Rfree.
------------------------------------------------------------------------------- Greg Costakes PhD Candidate Department of Structural Biology Purdue University Hockmeyer Hall, Room 320 240 S. Martin Jischke Drive, West Lafayette, IN 47907 -------------------------------------------------------------------------------- ** Hard work often pays of in time, but Procrastination always pays off now ** ----- Original Message ----- From: "Sam Arnosti" <meisam.nosr...@gmail.com> To: CCP4BB@JISCMAIL.AC.UK Sent: Monday, January 23, 2012 4:48:50 PM Subject: [ccp4bb] Problem with getting Rfree and Rf down Hi every one I have some crystals in the space group P3121. I collect 180 frames of data. My crystals do not diffract better than at most 2.0 angstrom, but the Rf barely goes below 23%, and Rfree also remains somewhere between 28-33%. I have tried to refine my data as much as I can. I do not know whether the problem is because of the bad diffraction or collecting extra frames. The structure factors are also high but they get better as the crystals diffract better. Thanks Sam
