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Dear phenix experts, I have sent the question to the buster discussion board one week ago. I think I'd better consult this problem on the active phenix discussion board. I recently solved a P1 crystal structure, 6 fold NCS at 1.6 angstrom resolution. I used lattice symmetry to generate test set in phenix. The phenix.refine gave me Rwork/Rfree = 0.1828/0.2081. There are pieces of positive and negative density for the compounds. So I tried buster refinement with autoncs, TLS. The density for the compounds are much improved, no obvious positive density. However, It generated Rwork/Rfree = 0.1801/0.1912. I also find similar R factor examples at the similar resolution in the buster wiki: https://www.globalphasing.com/buster/wiki/index.cgi?AutoBusterExample4chawat... Would the small gap between Rwrok and Rfree be an issue? I have not deposited buster refined PDB yet, would this acceptable? Any reference to help if any reviewer questions about the small gap? Thanks for your advice in advance. Best, Zheng