Re: [ccp4bb]: [new subject] TLS refinement

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

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> The publications describing the implmentation of TLS in restrain and
> tlsanal had, I seem to remember, some calculations of corrections to
> stereochemical restraints. Maybe if these were applied to the
> "traditionally" refined model then the differences might be accounted
> for.

The libration-corrected bond length is:

d = d_0 ( 1 + 1/2 [Tr(L) - n.L.n ] )

i.e. the correction is proportional to the magnitude of L. 
For side chain groups with large L, this is a significant correction.
For large TLS groups, L tends to be smaller and the correction
is probably negligible.

This correction can be seen at high resolution, and could be modelled
with small TLS groups. But I don't think it is significant for
medium/low resolution TLS which is what many are doing these days.

Martyn

-- 


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*                  Dr. Martyn Winn                                       *
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