[phenixbb] On estimating Unitary Structure Factor distribution

Andre LB Ambrosio andre at ifsc.usp.br
Wed May 15 05:35:51 PDT 2019


Dear all,

We seek to calculate the distribution of Unitary Structure Factors, Uhkl,
from a few datasets (at different maximum resolutions) for which the
corresponding atomic models are already available at the PDB; this
according to the formula (6.4), in the 2nd edition of Jan Drenth´s book:

Uhkl = exp[B*(sin^2(theta)/lambda^2)] x FOBShkl / F(000)

Hence, the following questions:

- Is there any macromolecular crystallography software that can compute
Uhkl as above, or equivalent?

- If not, would it be more correct to use the Wilson-B or the mean B from
the final model?

- How can F(000) be best estimated from the final model, which is not
necessarily always the most complete or best refined? Should we simply add
together the number of electrons for all the atoms refined in the
asymmetric unit (protein + ligands + solvent)?

Many thanks in advance and best wishes,


-- 
Andre LB Ambrosio
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