[Wien] Re : Supercell problem of Al2O3

[swati chaudhury]

Hi Michael and all Wien users,
I want to hit Al2O3 supercell problem once again.
Actually the problem is not yet resolved.I have done one more operation in a different way.
Putting 12 positions against single Al atom and 18 positions against single O atom, I just manually edit case.outputsgroup by adding all 36 symmetry operations for 167 (R-3c) hexagonal axes. But the same ROTDEF error occured as I told you before. 
  Is there any other way of adding the required (36) symmetry to the structure?
Please help me.
Regards,
Swati

Michael Fischer <dommiguel at gmx.de> wrote:
  Hello,

I think I can identify the problem, without knowing how to solve it (in 
an efficient way): The bottom of the struct-file must contain all 
symmetry operations of the hexagonal setting of space group 167, i.e. 
the 12 ones of the rhombohedral setting times 3 (translations in 
hexagonal cell) -> 36 symmetry operations.
As we constructed your struct-file by modifications of the one for the 
rhombohedral setting, it contains only 12 symmetry operations. This is 
where the error in the outputs-file comes from, where you read 
something like this:

The (multiplicity of this atom)*(number of pointgroup-operations) is 
NOT
= (number of spacegroup-operations)
MULT: 18 ISYM: 2 NSYM 12 <--- if 
NSYM was 36, everything would be fine
Check your struct file with sgroup -wien case.struct

I suspect the ROTDEF-error is connected to this, too.

As I said, I do not have a clue how to fix this efficiently. It could 
be possible to add the necessary symmetry operations at the bottom of 
the file by hand, but I think/hope that more experienced users will 
have a better solution.
Alternatively, you could specify all 30 atoms on formally inequivalent 
positions, each with MULT = 1.

Regards
Michael

_______________________________________________
Wien mailing list
Wien at zeus.theochem.tuwien.ac.at
http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien

-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://zeus.theochem.tuwien.ac.at/pipermail/wien/attachments/20070822/be546b62/attachment.html