Rarely do I disagree with the wit and wisdom of James Holton, but R1 is
not a property that Macromolecular World is unaware of.
R1 is just Rwork.
It's just R1 = Σ | |Fo| – |Fc| | / Σ |Fo|
However e.g. George Sheldrick's SHELXL reports it based on a 4 sig(F)
cutoff as well as on all data. Example:
R1 = 0.0421 for 27579 Fo > 4sig(Fo) and 0.0488 for all 30318 data
wR2 = 0.1153, GooF = S = 1.083, Restrained GooF = 1.083 for all data
(this Small Molecule World structure is not yet finished)
wR2 is a weighted R-factor based on |F|^2
See: http://shelx.uni-ac.gwdg.de/SHELX/shelxl_user_guide.pdf
The CIF file stores the two different R1 values as:
_refine_ls_R_factor_all 0.0488
_refine_ls_R_factor_gt 0.0421
So, don't expect that labeling anything "R1" uniquely defines whatever
sigma cutoff you are actually using. It's not implicit. You must
specify it but preferably don't report it at all, and just use it for
diagnostic purposes.
Phil Jeffrey
Princeton
On 10/16/17 11:02 AM, James Holton wrote:
If you suspect that weak data (such as all the spot-free hkls beyond
your anisotropic resoluiton limits) are driving up your Rwork/Rfree,
then a good sanity check is to compute "R1". Most macromolecular
crystallographers don't know what "R1" is, but it is not only
commonplace but required in small-molecule crystallography. All you do
