I am confused by the Britton/Murray-Rust plots in ctruncate.
My reading this morning has indicated that the "Britton" plot was
actually proposed by Fisher and Sweet 1980. Treatment of diffraction
data from crystals twinned by merohedry. Acta Crystallogr.A36:755--760
and plots the fraction of negative intensities after detwinning which
increases rapidly above the twin fraction.
The more often quoted Britton (1972) Acta A28 296-297 actually plot
I(2)/(I(1)+(I2) where I(1) and I(2) are twin related intensities and
the lowest value is the twin fraction
and Murray-Rust, P. (1973) Acta Cryst B29, 2559-2566 plot(F(1) against F(2)
which is bounded by lines of slope sqrrt[(1-twin)/(twin)] and
sqrrt[twin/(1-twin)]
Is then the ctruncate Murray-Rust Britton plot a detwin of F rather than I or
something else not documented (as far as I can find).
The documentation of the software does not seem to explain nor credit Fisher
and Sweet
Can anyone enlighten me as to the differences in the Britton plots in ctruncate.
Thanks
Nick
-------------------------------------------
Prof Nicholas H. Keep Executive Dean of School of Science Professor of
Biomolecular Science Crystallography, Institute for Structural and
Molecular Biology, Department of Biological Sciences Birkbeck,
University of London, Malet Street, Bloomsbury LONDON WC1E 7HX email
n.k...@mail.cryst.bbk.ac.uk Telephone 020-7631-6852 (Room G54a Office)
020-7631-6800 (Department Office) Fax 020-7631-6803 If you want to
access me in person you have to come to the crystallography entrance and
ring me or the department office from the internal phone by the door
