On Fri, 2011-06-10 at 12:48 -0700, Ethan Merritt wrote:
> I don't think that combination makes any sense. Whatever anisotropic
> is being described by the TLS parameters can also be fully described
> by the individual anisotropic U^ij terms. So the TLS parameters are
> entirely redundant, leading the minimization function to be poorly
> defined.
True, but the TLS refinement is implemented in refmac as separate step
preceding the positional/adp refinement. So in theory the TLS step will
go fine, and the anisotropic ADP refinement will take care of anisotropy
additional to TLS component. But of course you are absolutely right that
> I am virtually certain that refinement of individual anisotropic
> U^ij terms cannot be justified at 1.8A. Too many parameters,
> too few observations.
Matt reports that TLS lowers R/Rfree compared to anisotropic ADPs
"alone". Well that is good (TLS works!), but the question is if the TLS
+aniso is better than TLS+iso or, better yet, if R-values decrease when
going from Biso to Baniso.
Cheers,
Ed.
--
"I'd jump in myself, if I weren't so good at whistling."
Julian, King of Lemurs
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