[Wien] ROTDEF revisited

[Peter Blaha]

Dear Igor,

Space group #176 has only special positions:

2c: 1/3,2/3,1/4 and 2/3,1/3,3/4  
Your atom -1, however, is not exactly at 1/3 !

Similarly, the only 12-fold position is 12i and also there you have
some atomic positions exactly at 1/3, others differ slightly. 

For these reasons rotdef cannot find a symmetry operation which makes these
atoms equivalent and stops.

Please recheck the coordinates/equivalent atoms in your struct file.

Regards

> I am using WIEN2k_03, Structure File generator to
> generate a structure file for an intercalated
> graphite, MC6, symmetry group #176. I get a perfectly
> reasonable struct file (excerpts posted below), the
> program indetifies  correctly the symmetry group,
> produces the right symmtery operations, correct
> coordinates etc., but dstart bombs with the message
> 'ROTDEF error'. case.outputd file is empty, except for
> the header.
> 
> The struct file goes like this:
> 
> ...
> H   LATTICE,NONEQUIV.ATOMS:  2176_P63/m
> ...
> ATOM  -1: X=0.33333321 Y=0.66666679 Z=0.75000000
>           MULT= 2          ISPLIT= 4
> ATOM  -1:X= 0.66666679 Y=0.33333321 Z=0.25000000
> ....
> ATOM  -2: X=0.33333321 Y=0.33333333 Z=0.48000000
>           MULT=12          ISPLIT= 8
> ATOM  -2:X= 0.66666679 Y=0.66666667 Z=0.52000000
> ATOM  -2:X= 0.00000000 Y=0.33333321 Z=0.98000000
> ATOM  -2:X= 0.00000000 Y=0.66666679 Z=0.02000000
> ATOM  -2:X= 0.66666667 Y=0.00000000 Z=0.48000000
> ATOM  -2:X= 0.33333333 Y=0.00000000 Z=0.52000000
> ATOM  -2:X= 0.66666679 Y=0.66666667 Z=0.98000000
> ATOM  -2:X= 0.33333321 Y=0.33333333 Z=0.02000000
> ATOM  -2:X= 0.00000000 Y=0.66666679 Z=0.48000000
> ATOM  -2:X= 0.00000000 Y=0.33333321 Z=0.52000000
> ATOM  -2:X= 0.33333333 Y=0.00000000 Z=0.98000000
> ATOM  -2:X= 0.66666667 Y=0.00000000 Z=0.02000000
> ....
> 
> Any help will be highly appreciated.
> 
> 
> 		
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                                      P.Blaha
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Peter BLAHA, Inst.f. Materials Chemistry, TU Vienna, A-1060 Vienna
Phone: +43-1-58801-15671             FAX: +43-1-58801-15698
Email: blaha at theochem.tuwien.ac.at    WWW: http://info.tuwien.ac.at/theochem/
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