Ian Tickle replied:
(freezing & soaking can easily induce > 1% and sometimes > 5% change),
is surely the reason that Fo-Fo maps never caught on!
I've been curious about this unit cell constant mis-matching for a
while. If I understood well, Perutz tried to exploit the effect for
phasing prior to heavy atom methods. As the unit cell changes, the
diffraction peaks move, intensities change, and the fourier transform of
the molecule is sampled in between the Bragg peaks. Has anyone tried to
persue the idea since then?
Cheers,
Jon
See, eg, Bragg & Perutz, Proc. R. Soc. Lond. A 22 July 1952 vol. 213 no.
1115 425-435. doi: 10.1098/rspa.1952.0136
