Re: [ccp4bb]: Question about TLS refinement in refmac5

["M.D.Winn" <M.D.Winn@dl.ac.uk>]

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After the TLS refinement stage, the TLS parameters are
kept fixed, though of course they continue to contribute
to the calculated structure factor.

By default, the individual B values are then refined (as 
well as the coordinates) starting from the values in
XYZIN (aside from a uniform shift to take account of the
global contribution of scaling and TLS). However, if
the keyword "BFAC SET <val>" is used, then the B value
refinement starts from the specified constant value. This
is often a more stable way of doing it.

The former is (A). And the latter is more-or-less equivalent
to your (B).

Regards
Martyn

> Can someone clarify exactly what happens in refmac5 when one 
> performs a refinement such as the one shown in the TLS refinement
> example (ex 9 in the refmac5 docs)?  
> I understand the TLS refinement itself, but when refmac5 switches
> over to 
> 	REFInement BREFinement ISOTropic
> in the same run, what is happening then?   
> 
> Does it: 
> 
>    (A) 	keep the TLS parameters fixed but apply the TLS model on 
> 	top of the current state of the individual B values as it changes
> 	them?  
>    (B) 	translate the current TLS model into equivalent aniso Uij terms
> 	and then further refine an isotropic correction to the diagonal
> 	terms?
>    (C)	continue to refine the TLS parameters but now add in the 
> 	B terms as well?
>    (D)	some other possibility I haven't thought of?  	
> 
> 
> -- 
> Ethan A Merritt       merritt@u.washington.edu
> Biomolecular Structure Center Box 357742
> University of Washington, Seattle, WA 98195
> phone: (206)543-1421
> FAX:   (206)685-7002
> 


-- 


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*                  Dr. Martyn Winn                                       *
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