[Pw_forum] Symmetry Operations

[Giovanni Cangiani]

By changing the kinetic energy cutoff, you also modify the fft grid.
It can happen that the new grid is no longer compatible with the full
symmetry of your crystal. If you want you can fix the fft grid in the
input file (from pwdocs/INPUT_PW):

nr1,nr2,nr3  integer
             three-dimensional FFT mesh (hard grid) for charge
             density (and scf potential). If not specified
             the grid is calculated based on the cutoff for
             charge density (see also "dual")

for a reliable calculation please set nr1,nr2,nr3 values larger (or
equal) to those calculated by pw.x. 

	giovanni


On Sun, 2003-07-20 at 13:30, Katalin Gaal-Nagy wrote:
> Dear PWSCF users,
> 
> During some convergence tests following happened:
> 
> I used the same input-file and changed just the kinetic energy cutoff. In some 
> cases the progam used all possible symmetry operations and in some cases it used 
> less. What could be a reason for this?
> 
> Regards,
> Katalin Gaal-Nagy
> 
> 
> 
> ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,
> , >>>>>>>                Katalin Gaal-Nagy                 <<<<<<< ,
> ,    Gemeinerstr. 3                                 PHY 4.1.30     ,
> ,    93053 Regensburg                           Uni-Regensburg     ,
> ,    0941/7501574                                0941/943-2026     ,
> ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,
> , >>>>>>>    katalin.gaal-nagy at physik.uni-regensburg.de    <<<<<<< ,
> ,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,
> , >>>>>>>   Tr"aume nicht Dein Leben, lebe Deinen Traum    <<<<<<< ,
> ''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''''
> 
> _______________________________________________
> Pw_forum mailing list
> Pw_forum at pwscf.org
> http://www.democritos.it/mailman/listinfo/pw_forum