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> -----Original Message-----
> From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On 
> Behalf Of A Hibbert
> Sent: 17 November 2005 20:48
> To: [email protected]
> Subject: [ccp4bb]: More RFCORR/PHASER Questions
> 
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> ***          CCP4 home page http://www.ccp4.ac.uk         ***
> 
> 
> Sorry about all these questions, but I have a few more:
> 
> 1) For general self-education, I tried out the RFCORR/AMORE 
> script in the RFCORR documentation. From what I understand, 
> the X-rotation function shouldn't need a .tab file (from 
> TABLING) as normalized SFs from the model are already 
> calculated (and a TABLING run isn't included in the example). 
> Furthermore, the GENERATE command isn't executed. However, 
> AMORE complains that I haven't included a .tab file. Does 
> anyone know why?

I think Eleanor's right, the example scripts need updating to reflect
changes in the software since the scripts were last tested - sorry about
that!  After I made the script (and it certainly worked then!), I think
AMoRe was modified in such a way that it then expected to find a .tab
file even if it didn't need it (because the GENERATE step was being
skipped).  I think what happened was that Eleanor devised a way of using
E's within AMoRe that made my work-around script redundant.  But it's a
simple matter to generate a .tab and include it.

> 2) Do you think it's more sensitive doing a LOCKED ROTATION 
> in AMORE, then doing a translational search in PHASER, or 
> doing everything in PHASER and then running RFCORR?

In principle the locked RF should be more sensitive because you're
searching for the 2 NCS-related molecules simultaneously and
automatically eliminating solutions that are not consistent with the
SRF.  Note that the locked RF is not the same thing as an ordinary RF
with a dimer model, which clearly you should try if you can construct a
believable dimer (the difference is that the dimer RF includes in Fcalc
inter-molecular vectors between the molecules of the dimer, whereas the
locked RF doesn't, it only uses the intra-molecular vectors within both
molecules).

The RFCORR route should be reserved for cases where the SRF is not
readily interpretable, e.g. where the rotation group is not closed.
Having said that, it's undoubtedly true that Phaser's scoring function
is superior to that in Amore, so it's hard to say which combination of
methods will be more sensitive.  The obvious solution is to try them all
- but then in difficult cases I would do that anyway!

Clearly what we need for this kind of problem (which does after all pop
up quite frequently) is the best of both worlds - a locked RF using
Phaser's scoring function (Randy?).

-- Ian

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