[Pw_forum] Reply: ground state structure calculation -reg.,

[Savaş]

On 11/08/2013 08:31 AM, Suresh A wrote:
> Dear Everybody,
>                         Thank You for your reply.
> Dear Sava,
>                 In your reply you have quoted that " you need not 
> worry about symmetry conservation" is that means did i use any 
> symmetry conservation like card in my input file?
>
>
> Dear Giuseppe,
>                       First i did vc-relax with ecutwfc=50 and 
> ecutrho=200. for that input file that input file iget output as follows.
>         entering subroutine stress ...
>
>           total   stress  (Ry/bohr**3) (kbar)     P=   -0.08
>   -0.00000057  -0.00000025   0.00000000         -0.08 -0.04      0.00
>   -0.00000025  -0.00000057   0.00000000         -0.04 -0.08      0.00
>    0.00000000   0.00000000  -0.00000047          0.00 0.00     -0.07
>
>
>      bfgs converged in   7 scf cycles and   5 bfgs steps
>      (criteria: energy < 0.10E-04, force < 0.10E-03, cell < 0.20E+01)
>
>      End of BFGS Geometry Optimization
>
>      Final enthalpy =    -142.8393726978 Ry
> Begin final coordinates
>      new unit-cell volume =    365.14428 a.u.^3 ( 54.10880 Ang^3 )
>
> CELL_PARAMETERS (alat=  8.68089163)
>    0.951086548   0.000003754   0.000000000
>    0.000003754   0.951086548   0.000000000
>    0.000000000   0.000000000   0.617065718
>
>
>          entering subroutine stress ...
>
>           total   stress  (Ry/bohr**3) (kbar)     P= -233.71
>   -0.00161914  -0.00000028   0.00000000       -238.18 -0.04      0.00
>   -0.00000028  -0.00161914   0.00000000         -0.04 -238.18      0.00
>    0.00000000   0.00000000  -0.00152791          0.00 0.00   -224.76
>
>
>      Writing output data file pwscf.save
>
> there was a very large difference between last converged structures 
> kbar values so i suddenly change energy cuttoffs values to 200/800. 
> Futhermore i create this inputfile with the help of pwgui. Pwgui 
> automatically inserted exxdiv_treatment card which i didn't notice in 
> my calculation. I got some clues on my calculation. I will reply soon 
> to your answer.
>
> Dear Emine,
>                  I took pseudopotential as it is from quantum espresso 
> website. i didn't check on it whether it is hard pseudopotential or 
> soft one. the i choose higher cutoff because to reduce kbar difference 
> as i shown above.
> After i check my calculation i will reply to you.
>                          Thank you  all once again
>                   With Regards,
> A.Suresh,
> Project Fellow,
> Madurai Kamaraj University,
> Madurai.
>
>
> _______________________________________________
> Pw_forum mailing list
> Pw_forum at pwscf.org
> http://pwscf.org/mailman/listinfo/pw_forum

   Symmetry with orthogonal  axes is automatically conserved
   (primitive-cell) in vc-relax. Additionaly  "cell-factor" variable 
should also
   take your attention. Take its value more than its defaut
   (such as between 1.5-2.0). According to the output tiO2
   cell did not contract so much, but you can test whether or not the
   expansion of reciprocal space is enough to reinterpolate (fairly) the 
tables.

   Note : In your output it seems that symmetry (tetragonal) is breaked 
(slightly).
              I don't know why it's occured but make sure that all 
pseudopotential
              and cutoff related issues solved before attempt to solve 
symmetry
              related ones.

    Savaş AĞDUK
    Research Assistant
    Karabuk University
    Physics Department


-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.quantum-espresso.org/pipermail/users/attachments/20131108/3584b93c/attachment.html>