Dear All: I am refining a structure with TLS parameters in REFMAC5. When I run the Procheck, some warning appear like below:
--- generate density --- WARNING: Determinant(U) =< 0 : -0.000475003297 for atom: C , res: 18, CHAIN: 1 U: 0.08410 0.31220 0.17130 0.02360 0.04920 -0.20800 atom will not be used WARNING: Determinant(U) =< 0 : -0.000683392049 for atom: O , res: 18, CHAIN: 1 U: 0.08280 0.32110 0.15860 0.01930 0.05420 -0.20470 atom will not be used WARNING: Determinant(U) =< 0 : -0.000691463996 for atom: N , res: 19, CHAIN: 1 U: 0.07950 0.30660 0.17030 0.01890 0.04760 -0.21570 atom will not be used What does this warning mean? Does this mean something about the model quality? But I have found nothing unusual in this position, when I look at this part of my strucutre model with its well defined density. Is there anyone who have met the same warning? How to deal with it? Thanks -- Jiamu Du State Key Laboratory of Molecular Biology Institute of Biochemistry and Cell Biology Shanghai Institutes for Biological Sciences Chinese Academy of Sciences (CAS)