[CP2K-user] Max. gradient convergence criterion.

Tommaso Civitarese civitares... at gmail.com
Wed Dec 5 09:07:47 UTC 2018


Dear all,
I am performing a direct-cell optimization of a graphene nano ribbon: the 
optimization goes well but I am a bit confused about the meaning of the 
convergence criterion 'Max. gradient' that is, how explained in the 
tutorial 'Electronic structure using DFT', the maximal force (seen over all 
atoms).  This number, from what I understood, is the maximum force that you 
can find in your system acting on the atoms but if I compare this number to 
the forces print on the specific output file (where there are the three 
components of the forces acting on the atoms at a specific step) I did not 
find any match.
So, my questions are:
- what does 'maximal force (seen over all atoms)' means?
- If I would like that each component of the forces acting on the atoms are 
lower than a certain value (for example 10^-5 eV/ang), how can I do? There 
is a specific flag for this? 
Thank you very much for your attention.
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