[ccp4bb] truncate Wilson printout

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CCP4bb <-- 2007 <-- April 2007 <-- 23 April 2007

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Subject: truncate Wilson printout
From: Bernhard Rupp bernhardrupp {- at -} SBCGLOBAL {- dot -} NET
Date: 2007-04-23

Dear All,

there is one line in the TRUNCATE output that makes
me question my sanity.

Under the Wilson plot the log states:

Least squares straight line gives: B = 12.743 SCALE = 22.25070
where F(absolute)**2 = SCALE*F(observed)**2*EXP(-B*2*SINTH**2/L**2)

This is somewhat counterintuitive, because in order to get the
attenuated reflections fobs**2 *UP* to the unattenuated fabs**2 I would
assume that I have to multiply with the inverse of the B-factor attenuation,
EXP(B*2*SINTH**2/L**2)

If I look at the plot, then plot is indeed from a graph
ln[(fobs**2)/fabs**2] = ln(k)-2B(sintol**2)

thus

ln(fobs**2)=ln(fabs**2)+ln(k)-2B(sintol**2) =

fobs**2 =k*(fabs**2)*exp(-2B(sintol**2))

which essentially is the opposite of what truncate says,
I thus wonder if the inverse expression for bringing
relative to absolute intensities, i.e., scaling back
should be in truncate terms

F(absolute)**2 = SCALE*F(observed)**2*EXP(B*2*SINTH**2/L**2)

I know this is for sure the right way to bring
fobses back up to unitary Us and normalized Es.

What am I missing here?

Thx, br
--------------------------------------------
Bernhard Rupp
www.ruppweb.org
--------------------------------------------

CCP4bb navigation

CCP4bb <-- 2007 <-- April 2007 <-- 23 April 2007

Previous message:
Subject: sealing deep wells
From: Mario Sanches msanches {- at -} LNLS {- dot -} BR
Date: 2007-04-23

Next message:
Subject: GTBIO 2007 Meeting
From: Prakash Rucktooa prakash {- dot -} rucktooa {- at -} IBL {- dot -} FR
Date: 2007-04-24