[CP2K-user] [CP2K:12866] Re: Convergence with CUTOFF

Augustin Bussy august... at chem.uzh.ch
Mon Feb 10 08:52:09 UTC 2020


you can run a first geometry optimization run with a lower EPS_SCF so 
that it converges faster to an approximate solution. Once you are there 
you can restart with a tighter threshold. As for the initial position of 
the molecules, I am not familiar with your system myself, I am afraid.



On 2/8/20 3:20 PM, coko312 wrote:
> Thank you very much both of you for these answers!
> Indeed I can reduce the size of my box to 10 Angstroms ; for one Na+ 
> ion and a CO2 molecule, I need to use 12 Angstroms. So I am confident 
> now that nothing is crazy with my simulation, but I guess I need a 
> little more computing power and parallel simulations.
> For a single Na+ ion, it works also very well with lower EPS_SCF 
> (1.E-8). However, with this EPS_SCF I have some difficulties in making 
> the SCF cycle converge with one Na+ ion and a CO2 molecule. I suspect 
> it is due to the initial position of my CO2 molecule. What would you 
> use as a reasonable distance/orientation, and how many iterations of 
> the geometry optimization procedure would you expect (50, 100, 500 ... )?
> Le lundi 27 janvier 2020 09:02:14 UTC+1, coko312 a écrit :
>     Dear all,
>     I am a cp2k-DFT beginner so the answer to this question may seem
>     obvious to you, but it would help me a lot!
>     I try to converge the total energy of a single Na+ ion as a
>     function of the energy CUTOFF, but the convergence is very slow
>     and even using 900 Ry is not fully satisfactory for what I want to
>     do. Even with no experience with this system, I would not expect
>     the computation to last several hours on a single processor for
>     only 1 atom. I have attached my input-output files. What should I
>     modify to be able to use a more reasonable CUTOFF?
>     NB : the computation is non-periodic because I would like, next,
>     to add more atoms around to compute interaction energies between
>     these little "clusters" and various types of molecules.
>     Best,
> -- 
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Augustin Bussy
PhD Student

University of Zurich
Augustin Bussy
Department of Chemistry
Research Group Hutter
Winterthurerstrasse 190
CH-8057 Zurich

Tel: +41 44 635 4490

august... at chem.uzh.ch

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