[Wien] ELNES: q orientation

[Bertoni Giovanni]

Thanks Kevin!

so if I understood, the crystal basis I have to referred the Euler
angles in ELNES is the CONVENTIONAL crystal basis (a,b,c and mutually
orthogonals...) is it true?
The definition of Euler angles itself need cartesian coordinates I
think...
Best regards
Giovanni


Jorissen Kevin a écrit :
> 
> Hi Giovanni,
> 
> you definitely need option H (not F).  Just keep Thetabragg = 0 ; it's a special option which is rarely used.  If you want k0 and k to be parallel, put ThetaX and ThetaY to zero.  These two angles control the orientation of k with respect to k0.
> The Euler angles define the orientation of the beam with respect to the crystal.  They are indeed defined for a transformation between two carthesian bases (the Bravais matrix is used internally by the telnes program) : the laboratory (== beam) basis, and a carthesian crystal basis (with its z axis parallel to the c basis vector of the crystal lattice).  So, to hit your sample along the c-direction, you would use Euler angles 0,0,0.  To put the beam in the a,b - plane, you could use 0,90,0.
> 
> 
> kind regards,
> Kevin.
> EMAT
> University of Antwerp, Belgium.
> 
> 
> 
>         -----Oorspronkelijk bericht-----
>         Van: Bertoni Giovanni [mailto:giovanni at cemes.fr]
>         Verzonden: ma 12/1/2003 9:28
>         Aan: wien at zeus.theochem.tuwien.ac.at
>         CC:
>         Onderwerp: [Wien] ELNES: q orientation
> 
> 
> 
>         Dear users,
>         could someone explain me how to set an orientation of q in ELNES program
>         (case.innes) ?
>         let's q = k0 - k'
>         if I take option N, I integrate on the full solid angle, isn't it (all
>         q) ?
>         so I need F or H.
>         is k' oriented along z' of the observer ?
>         so if I put 2*thetaBragg=0  k0 is parrallel to k' and parallel to q?
>         how can I orient q (or k0 if it is parallel in the case) ?
> 
>         the Euler angles of the observer are respect to the x, y, z, cartesian
>         axes?
>         or respect to the vector of the bravais matrix defined in tab 4.4 of pag
>         39 of the manual
>         (treating the case.struct file)
>         Please tell me. I am a little bit confusing....
>         Thank you.
>         giovanni
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> 
> 
> 
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