[phenixbb] neutron scattering table for specific metal isotope

[Leif Hanson]

Tim,
As I understand joint refinement (although Paul Langan and Marat
Mustyakimov can give a better answer), the X-ray data are used to establish
the non-H atom positions, and n0 data to establish H and D positions. From
a practical standpoint, shelx was wonderful for defining the scattering
factors of the atoms. But we had issues with the length of the input file
since we had to create free variables for each of the exchangeable
hydrogens. With more than 400 residues this got a little crazy.
Leif

On Thu, Dec 4, 2014 at 4:14 AM, Tim Gruene <tg at shelx.uni-ac.gwdg.de> wrote:

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> Hi Maxime,
>
> you could use shelxl for refinement - it uses the values from the
> Neutron Data Booklet for the most abundant isotopes, and you can mix
> them with your own scattering values without even looking at the code.
> You can even take into account incoherent contributions by adjusting
> the f' and f'' values on the SFAC command like
> NEUT
> SFAC C H N O S D
> SFAC  FeX   0 0 0 0 0 0 0 0  4.20   0 0 11.220 1.23 56
> SFAC Co
>
> if you have e.g. Fe-54
>
> If you want to have a joint refinement between X-ray and neutron data,
> I recommend using the X-ray structure by external restraints rather
> than mixing two different types of experiments. You won't e.g need to
> worry about different effective hydrogen bond lengths. Published
> restraints for hydrogen atoms to use with neutron data are available
> from my web-site, for ligands they can be generated by the grade-server.
>
> Regards,
> Tim
>
>
> On 12/03/2014 10:36 PM, Maxime Cuypers wrote:
> > Hello,
> >
> > I would like to alter the neutron scattering table for
> > phenix.refine so that it takes into account the correct bcoherent
> > value for the metal isotope present in my structure. the difference
> > is significative between the natural occurence bcoh... i have been
> > looking around in chem_data but could not find the neutron
> > scattering tables. does anyone have any idea where to look please?
> >
> > cheerios
> >
> >
> >
> > _______________________________________________ phenixbb mailing
> > list phenixbb at phenix-online.org
> > http://phenix-online.org/mailman/listinfo/phenixbb
> >
>
> - --
> - --
> Dr Tim Gruene
> Institut fuer anorganische Chemie
> Tammannstr. 4
> D-37077 Goettingen
>
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