[Wien] question about symmetry

[Peter Blaha]

Of course, the symmetry programs do not "alllow" a wrong symmetry.

The way to do it is very simple:

Setup your struct file with some internal parameters which lead to the desired symmetry.

AFTER init_lapw change these internal parameters to whatever you want and run the scf-cycle.

Do NOT run init_lapw anymore.

PS: Of course this works only in ONE direction, i.e. you must run the initialization
with a lower symmetry and change it later to some actually higher one.
But of course you MUST NOT do the opposite.

Hong Jiang schrieb:
> Dear Wien2k developers and users,
> I have a question about the use of the symmetry in wien2k. I am 
> calculating a tetragonal lattice with the symmetry of P42/nmc. But for 
> some special value of the internal lattice parameter,
> the lattice symmetry becomes I4/mmm. I want to do calculations still 
> with P42/nmc, but apparently using init_lapw in a standard way does not 
> allow me to that.
> Even though init_lapw does allow me to use original struct file after 
> running "sgroup",  "symmetry"  does not, which stops with the warning 
> message
> 
>    STOP: YOU MUST MOVE THE ORIGIN OF THE UNIT CELL (see  tetra.outputs )
> 
> I found one way to avoid that by
>    1)   x -f tetra symmetry
>    2)   init_lapw -s lstart  -f tetra
> 
> The first step is necessary because when generating *.in2, init_lapw 
> requires the output from symmetry, *.in2_sy .
> I am wondering  whether the way I did is legitimate. 
> If the answer is yes, should "symmetry" in init_lapw also allow the user 
> to choose the original struct instead of "STOP: YOU MUST MOVE THE ORIGIN 
> OF THE UNIT CELL" ?
> Apparently the inquiry after 'symmetry' in init_lapw
>      -----> continue with lstart or edit the tetra.struct_st file (c/e/x)
> is not working in the way as it is supposed to do.  
> Thank you very much in advance.
> 
> Best regards,
>    Hong
> 
> 
> 
> 
>  >   sgroup      (11:26:15) 0.000u 0.000s 0:00.01 0.0%   0+0k 0+0io 0pf+0w
>   Names of point group: 4/mmm   4/m 2/m 2/m    D4h
>   Names of point group: -4m2   -4m2   D2d
> Number and name of space group: 139 (I 4/m m m)
> warning: !!! Bravais lattice has changed.
> -----> check in  tetra.outputsgroup  for proper symmetry, compare
>        with your struct file and later with  tetra.outputs
>        sgroup has also produced a new struct file based on your old one.
>        If you see warnings above, consider to use the newly generated
>        struct file, which you can view (edit) now.
> -----> continue with symmetry or edit tetra.struct_sgroup ? (c/e)
> c
> 
> --- symmetry ---
> 
>  >   symmetry    (11:26:22) 0.001u 0.002s 0:00.06 0.0%   0+0k 0+0io 0pf+0w
> WARNING: YOU MUST MOVE THE ORIGIN (see  tetra.outputs )
> -----> check in  tetra.outputs  the symmetry operations,
>        the point symmetries and compare with results from sgroup
> -----> continue with lstart or edit the tetra.struct_st file (c/e/x)
> c
> STOP: YOU MUST MOVE THE ORIGIN OF THE UNIT CELL (see  tetra.outputs )
> 
> _______________________________________________
> Wien mailing list
> Wien at zeus.theochem.tuwien.ac.at
> http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien

-- 

                                       P.Blaha
--------------------------------------------------------------------------
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/
--------------------------------------------------------------------------