[Wien] irrep and sg 204

[Víctor Luaña Cabal]

On Thu, May 07, 2015 at 11:51:37AM +0200, torsten weissbach wrote:
> my question regards the Irrep program. I am interested in a  
> representation analysis at Gamma point for a symmorphic space group (no. 
> 204). The point group is identified as Th, but then the program crashes 
> saying "trsym:cannot find class". The calculation is just PBE.

Torsten,

The gamma point (\vec{k} = [0,0,0]) is always the maximal symmetry
point. In space group 204 (Pa-3), the symmetry is m-3:

<http://www.cryst.ehu.es/cgi-bin/cryst/programs/nph-kv-list>

Examine the first Brillouin zone at

<http://www.cryst.ehu.es/cgi-bin/cryst/programs/nph-kv-list?gnum=205&fig=fm3qp&what=data>

In molecular symmetry parlance m-3 is the C_{3v}, but if we want
to obtain the character table for this group look at the answer
of the Bilbao cryst server:

#########################################################################
Space Groups and Representations.
---------------------------------

This program calculates irreducible representations of space
groups. Space group irreps are labeled by k-vector star and a symbol
for the little group representation. In this new version, thanks to
the collaboration of H. Stokes, the assigned irrep labels coincide
with the notation used in Cracknell-Davies-Miller-Love tables [1] and
ISOTROPY. The program is also linked to KVEC for an automatic choice
of the k-vector. The program is still under construction.

You have to introduce the space group number, you can give this number,
if you know it, or you can choose it from the table with the space
group numbers and symbols if you click on the button choose it. When
you click on the botton next you will find a form where you have to
introduce the k vector.

[1] Cracknell, A. P., Davies, B.L., Miller, S. C., and Love,
W. F. (1979). Kronecker Product Tables. Vol. 1. General Introduction
and Tables of Irreducible Representations of Space Groups. New York:
IFI/Plenum.


If you are using this program in the preparation of a paper, please
cite it in the following form:

M. I. Aroyo, A. Kirov, C. Capillas, J. M. Perez-Mato &
H. Wondratschek."Bilbao Crystallographic Server II: Representations
of crystallographic point groups and space groups". Acta Cryst. A62,
115-128 (2006).
########################################################################

So: be careful to determine if you are using a 

200 	Pm-3
201 	Pn-3
202 	Fm-3
203 	Fd-3
204 	Im-3
205 	Pa-3
206 	Ia-3

space group in your calculations.

Regards,
       Dr. Víctor Luaña
--
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! Dr.Víctor Luaña, in silico chemist & prof. ! 
! Departamento de Química Física y Analítica ! 
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