[QE-users] ?==?utf-8?q? Same run not accelerated when starting from converged rho and wfc

[Antoine Jay]

Dear Stephano,
adding diago_thr_int=1.0D-8 does not change the first conv_thr (exept the average#of iterations)
As you said, the first value 1.0D-2 is detected to  be too large and is updated to 6.0D-9 so I don't see why changing manually the first value would change something if it is already automatically changed...

Antoine Jay
LAAS-CNRS
Toulouse, France

Le Samedi, Août 15, 2020 17:10 CEST, Stefano de Gironcoli <degironc at sissa.it> a écrit:
  
Hi Antoine,
  don't know exactly why you get this result but one thing you can try is to set diag_thr_init ~ conv_thr/Nelec/10 so the first diagonalization is pushed tighter (if the wfcs are already very good it should not take too many iterations) and the computed dr2 estimate should be more faithful
  now diag_thr_int is 1.d-2 then updated to 6.e-9 which is consistent with conv_thr ~6.d-5...
  idk. you can try
  stefano
  On 14/08/20 17:09, Antoine Jay wrote:Dear all,

I'am doing two consecutive scf calculations with exactly the same structure and parameters by calling qe6.5 as a library (attached output files).
For the second call, I use the options:
startingwfc='file' and input_rho ='rho.in'
where these inputs are the converged wfc1.dat and charge-density.dat of the first step.
Here I face two problems:

-I expected that the initial scf accuracy is 10^-11 as obtained at the end of the first step, but it is only 10^-4.
How is it possible to explain such a decrease? I generally loose only 2 orders of magnitude by doing this.

-Even with less scf iterations, the cpu time is greater.
Is it possible that some extra memory is allocated by qe when input rho and wfc are asked, and not desallocated?

Note that until now, I have these troubles only when I use paw pseudopotentials on big systems.

Regards,

Antoine Jay
LAAS-CNRS
Toulouse France





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