[CP2K-user] [CP2K:18939] Re: Increase of the SCF cycles along an AIMD run

[captain mus]

Hi Dune 

The origin of the increase of the SCF cycle in principle is because the 
calculation still trying to find the best wave functions, this is why if 
you look at your output (grep time out.out) the first step of SCF 
convergence always takes longer than the later. Since you start from the 
restart file, assume that you have the wfn file (i.e., file-RESTART.wfn) 
then you can use it to decrease the SCF cycle and speed up the calculation 
with the following
-------------------------------------------------------------------
&SCF
       ....
           SCF_GUESS  HISTORY_RESTART
      ....
&END SCF 
-------------------------------------------------------------------

Hope it help 

Best
Saleh


On Monday, June 5, 2023 at 7:09:38 PM UTC+2 Dune André wrote:

> Dear all,
>
> I am facing an issue while running AIMD simulations of a box of ~1000 
> atoms. The system is an amorphous MOF made of Fe linked by benzene 
> tricarboxylate (named Fe-BTC).
>
> I use PBE functional with DZVP basis set and GTH pseudopotential ; DIIS 
> method and FULL_KINETIC preconditioner. I perform the calculation from a 
> restart file. The first steps of the MD are quite fast with ~10 SCF steps 
> per MD step. But along the AIMD run, the SCF cycles become longer and 
> longer (~100 SCF steps per MD step). 
>
> I tried to use other OT method such as CG or other preconditioner such as 
> FULL_SINGLE_INVERSE but in both cases the SCF cycles are taking too much 
> time and sometimes fail to converge. Besides, FULL_ALL preconditioner is 
> too computationally expensive in terms of memory.
>
> Do you have some ideas of the origin of this increase of the SCF cycles? I 
> attached the restart file to the message. 
>
> Thanks in advance for your help,
>
> Kind regards,
>
> Dune André
>

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