On 8 September 2015 at 12:40, Christina Möller <c.moeller@xxxxxxxxxxxxx>
wrote:
Dear Edward and relax users,
I would like to know the weights (ci) of an ellipsoidal diffusion. It
can possibly be extracted by the weights.py script. Unfortunately, I
could not find out how to use this script and which input files are
needed. Can anyone give me a hint how to obtain the weights?
Hi Christina,
Which version of relax are you using? There is no weights.py script,
however you may be referring directly to the relax source code itself
(at http://www.nmr-relax.com/api/3.3/lib.diffusion.weights-module.html
and http://www.nmr-relax.com/api/3.3/lib.diffusion.weights-pysrc.html
). These weights are physical constants as derived and presented in
the original papers of Perrin 1934
(http://dx.doi.org/10.1051/jphysrad:01934005010049700 ) and Perrin
1936 http://dx.doi.org/10.1051/jphysrad:01936007010100 ). There are
written in French, but I have included these in the relax manual at
http://www.nmr-relax.com/manual/The_weights_of_the_ellipsoid.html .
From these equations, you should be able to calculate the weights
yourself. Note that they are dependent on the XH bond vector
orientation, specifically their projection onto the diffusion tensor.
It will probably be easier to calculate these yourself for each data
point, rather than using the relax code. If you would prefer to use
the relax code, and know Python scripting, then you'll need to create
2 data containers (class instances) with the appropriate data,
pre-calculating the vector projection onto the diffusion tensor
(data.dx, data.dy, data.dz in the code) and passing these containers
into the lib.diffusion.calc_ellipsoid_ci() function. I hope this
helps.
Regards,
Edward
Re: weights of diffusion