[ase-users] spacegroup question

[Lasse Bjerg]

Hi Lars

Space group no. 123 does not connect (0,0,0) to (0.5,0.5,0.0), so the 
two positions are two distinct positions, and both should be given when 
creating the structure. The connections of space group no. 123 can be 
seen here:
http://img.chem.ucl.ac.uk/sgp/large/123az1.htm
Putting an atom on position (x,y,z) will automatically give you atoms on 
positions 2-16.

Lasse

On 2011-09-07 16:06, Lars Grabow wrote:
> Hi,
>
> I tried to use the ase spacegroup package to make the L_10 bulk 
> structure (http://cst-www.nrl.navy.mil/lattice/struk/l1_0.html)
>
> I expected to get the correct results with this command:
>
> bulk = crystal(['Cu','Au'],[(0,0,0),(0.5,0.0,0.5)], spacegroup=123, 
> cellpar=[a,a,c,90,90,90])
>
> However, when I build this bulk structure, one Cu atom seems to be 
> missing.
> The correct structure is obtained when I add an extra Cu atom like this:
>
> bulk = crystal(['Cu','Cu','Au'],[(0,0,0),(0.5,0.5,0.0),(0.5,0.0,0.5)], 
> spacegroup=123, cellpar=[a,a,c,90,90,90])
>
> Am I using the spacegroup package correctly, or is this possibly a bug?
>
> Thanks!
> Lars
>
> -------------------------------------------------------------------------------------------------------------
> Lars C. Grabow
> Assistant Professor of Chemical and Biomolecular Engineering
> University of Houston
> S341 Engineering Building 1
> Houston, TX 77204-4004
> email: grabow at uh.edu <mailto:grabow at uh.edu>web: 
> http://www.chee.uh.edu/faculty/grabow
> phone: (+1) 713-743-9899fax: (+1) 713-743-4323
>
>
>
>
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-- 
Lasse Bjerg
Visiting PhD Student
Massachusetts Institute of Technology
77 Massachusetts Avenue
Room 13-4042
Cambridge, MA 02139
office (+1) 617-258-0222
mobile (+1) 857-272-0769
email bjerg at mit.edu



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