[Wien] 'x symmetry' issue

[Laurence Marks]

This is almost certainly related to numerical precision. There are so e
partial cures for this in code that traps 1/3 and 2/3 for hexagonal, but it
is not complete and there are some numerical issues with the rotation
matrices as well; you can look at SymmRot.f in SRC_lapw0. It probably needs
expansion and use in more areas, which is not a 1 minute fix.

Two patches may work:
1) use "init_lapw ....-s sgoup" to skip symmetry
2) generate the Symm using a smaller cell than paste those onto the end of
the struct file. Maybe also use x patchsymm as well. You may still need to
do 1!

___
Emeritus Professor Laurence Marks (Laurie)
Department of Materials Science and Engineering, Northwestern University
www.numis.northwestern.edu
"Research is to see what everybody else has seen, and to think what nobody
else has thought" Albert Szent-Györgyi

On Fri, May 29, 2026, 18:08 Gavin Abo <gabo13279 at gmail.com> wrote:

> Seems like it could be related to numerical precision.  Taking the
> test2.struct that you sent, I also see the "2 missing" with WIEN2k 24.1 for
> Y=0.66666666 for ATOM 74 and 98, but it seems to go away if Y=0.66666667 is
> used:
>
> username at computername:~/wiendata/test2$ grep "ATOM  74" test2.struct
> ATOM  74: X=0.33333333 Y=0.66666666 Z=0.70000000
> username at computername:~/wiendata/test2$ grep "ATOM  98" test2.struct
> ATOM  98: X=0.33333333 Y=0.66666666 Z=0.50000000
> username at computername:~/wiendata/test2$ x symmetry
>  SPACE GROUP DOES NOT CONTAIN INVERSION
> STOP 2 missing
> 0.141u 0.011s 0:00.15 100.0%    0+0k 0+664io 0pf+0w
>
> username at computername:~/wiendata/test2$ gedit test2.struct
> username at computername:~/wiendata/test2$ grep "ATOM  74" test2.struct
> ATOM  74: X=0.33333333 Y=0.66666667 Z=0.70000000
> username at computername:~/wiendata/test2$ grep "ATOM  98" test2.struct
> ATOM  98: X=0.33333333 Y=0.66666667 Z=0.50000000
> username at computername:~/wiendata/test2$ x symmetry
>  SPACE GROUP DOES NOT CONTAIN INVERSION
> 0.190u 0.010s 0:00.20 100.0%    0+0k 0+728io 0pf+0w
>
> Kind Regards,
> Gavin
> WIEN2k user
>
> On 5/29/2026 2:57 AM, Stefaan Cottenier via Wien wrote:
>
>
> (I'm re-sending this message, as the attached struct file in my previous
> post was too large. Now it's gzipped and smaller)
>
>
> Dear WIEN2k developers,
>
> I ran into an issue that is probably a communication problem between
> sgroup and symmetry. The attached struct file is a large supercell (Ag
> substitutional impurity in hcp-Zn), that has been created by sgroup as
> space group P-6 with 102 inequivalent positions.
>
> When running 'x symmetry' in a folder that contains only this struct file,
> it fails for the 18th inequivalent position (Zn17):
>
> ATOM  18: X=0.33333333 Y=0.66666666 Z=0.10000000
>           MULT= 2          ISPLIT= 8
>       18: X=0.33333333 Y=0.66666666 Z=0.90000000
> Zn17       NPT=  781  R0=0.00005000 RMT=    2.3700   Z: 30.0
> LOCAL ROT MATRIX:    1.0000000 0.0000000 0.0000000
>                      0.0000000 1.0000000 0.0000000
>                      0.0000000 0.0000000 1.0000000
>
> The last lines of case.outputs read:
>
>  ATOM:          18
> Zn17       operation #  1     1
> Zn17       operation # 22     3 || -z
>   pointgroup is 2 (neg. iatnr!!)
>   axes should be: 2 || z
>
> Both case.struct_st and case.in2_sy (that are produced by 'x symmetry')
> are truncated after the 17th inequivalent position. The screen output is:
>
>  SPACE GROUP DOES NOT CONTAIN INVERSION
> 2 missing
> 0.010u 0.003s 0:00.01 100.0%    0+0k 0+0io 0pf+0w
>
> It looks like symmetry finds a point group "2", and does not recognize
> that one.
>
> Not sure whether the problem is in sgroup, in symmetry, or in the way how
> they communicate to each other.
>
> This was done with version 24.1. Any suggestion how to fix this?
>
> Best regards,
> Stefaan
>
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