[Wien] Re : Supercell problem of Al2O3

[swati chaudhury]

Hi Micheal and all Wien users,
  Many many thanks for constant helping.
  At last my problem may be resolved.According to your advice,putting 30 positions for each indivisual atom,scf is runing smothly for normal cell.
  One more question again.The number of symmetry in structure file is 1(expected 36 for hexagonal).So the calculation is correct or not?
  In addition,for (2 2 2) supercell with vacuum slab 4 bohr, the calculation is ended in dstart (dstart error-insufficient virtual memory problem).Then I have tried with (2 2 1) supercell with vacuum slab 4 bohr, dstart is now runing. No such error message or warning.In 1st case no of atom in supercell is 280 whereas in 2nd i.e. 120 .Is there any limitation of maximum number of atoms in Wien?
  Suggest 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

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