[Wien] In the calculation of elastic properties why ​​​​​rhombohedral lattice parameter needs same k-mesh as used in pristine case

[Luis Ogando]

Dear Bhamu,

    Please, check if init_lpaw did not rotate your cell. Perhapes 18.184512
is now at y axis, b parameter.
   All the best,
             Luis

Em sex, 17 de mai de 2019 às 07:49, Dr. K. C. Bhamu <kcbhamu85 at gmail.com>
escreveu:

> Dear Wien2k users,
>
> I am running a cubic (F) system having a=b=c=10.446600Bohr. The default
> k-mesh size is 14 14 14 (3000kpt in FBZ).
> I applied tetragonal and rhombohedral strain on optimized lattice
> parameters (on above a,b,c) and the resultant strained a/b/c are 10.429247
> /10.429247/10.481393 Bohr for tetragonal strain and 7.386862/7.386862/
> 18.184512 Bohr for rhombohedral strain.
>
> My script advise me to use 20 20 8 kmesh size for the rhombohedral case
> and "14 14 14" (as there is only slight change in a/b/c) for tetragonal
> case.
>
> But for the rhombohedral case I am not able to use 20 20 8 mesh size and
> the kgen program suggest me to use equal mesh in x and z direction (see
> below in blue).
>
> Could you someone please advice me why I can not use the mesh size  20 20
> 8 for the rhombohedral case?
>
> I may be convinced about my doubt because I am having  equal "length of
> reciprocal lattice vectors:   1.041   1.041   1.041".  Am I right? If so,
> then also I need to know why a lattice parameter which is almost double in
> one direct wrt original cubic latice need the same k-points as used in case
> of cubic case. The answer may be somewhere in symmetry operations but I
> could not completely understand it.
>
>
>
>            6  symmetry operations without inversion
>  inversion added (non-spinpolarized non-so calculation)
>   NUMBER OF K-POINTS IN WHOLE CELL: (0 allows to specify 3 divisions of G)
> 0
>  length of reciprocal lattice vectors:   1.041   1.041   1.041   0.000
> 0.000   0.000
>   Specify 3 mesh-divisions (n1,n2,n3):
> 20 20 8
>  Lattice symmetry requires equal mesh in x and z direction
>   Specify 3 mesh-divisions (n1,n2,n3):
>
>
> regards
> Bhamu
>
>
> _______________________________________________
> Wien mailing list
> Wien at zeus.theochem.tuwien.ac.at
> http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien
> SEARCH the MAILING-LIST at:
> http://www.mail-archive.com/wien@zeus.theochem.tuwien.ac.at/index.html
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://zeus.theochem.tuwien.ac.at/pipermail/wien/attachments/20190517/a7a13abb/attachment.html>