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)
