For the sake of a thought experiment we can assume the refinement
is implemented with infinite-precision arithmetic. And for actually
...
terms in the 2n'd derivative matrix are ignored?). Two ncs-related atoms
can move in agreement with the ncs-restraint without penalty from the
near-infinite ncs-weight, and will if by doing so they improve the
agreement with the X-ray data?
Well, good luck with that. (What with thousands of atoms, noise in the
incomplete data, issues of numerical precision, genuine local NCS breakdown in
the crystal, ...)
I think you may have missed the operative words in my reply - "in practice".
I'm sure that somewhere there is now a student who misconstrues Ian's thought
experiment to mean that a humongous NCS-restraint weight is as good as
constraints (and this student wouldn't be the first either). So: don't try
this at home, kids!
On behalf of the Royal Society for the Prevention of Cruelty against Models,
--Grandpa
******************************************************************
Gerard J. Kleywegt
Dept. of Cell & Molecular Biology University of Uppsala
Biomedical Centre Box 596
SE-751 24 Uppsala SWEDEN
http://xray.bmc.uu.se/gerard/ mailto:[email protected]
******************************************************************
The opinions in this message are fictional. Any similarity
to actual opinions, living or dead, is purely coincidental.
******************************************************************
