[CP2K-user] Convergence with CUTOFF

coko312 cok... at gmail.com
Sat Feb 8 14:20:34 UTC 2020

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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