[ase-users] spacegroup question

[Lasse Bjerg]

Furthermore, the space group no. 123 must refer to the primitive (and 
also tetragonal) unit cell with a = b = 1./sqrt(2) * old_a, c = old_c; 
and Au at (0, 0, 0) and Cu at (½, ½, ½).

On 2011-09-07 17:56, Lasse Bjerg wrote:
> 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
> emailbjerg at mit.edu
>
>
>
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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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