[CP2K:2254] Re: convergence & cutoff madness

Toon Verstraelen toon.ver... at UGent.be
Mon Sep 7 12:07:16 UTC 2009

Fawzi Mohamed wrote:
> Hi,
> some comments:
> 1) do you trust your cp2k version, can you reproduce the regtest  
> results within a reasonable error?
> 2) convergence wrt. cutoff is not variational
> 3) if the cutoff is too low derivatives (and KS matrix) are wrong, and  
> thus convergence difficult (I would say the lowest cutoff is around  
> 280 for your case)
> 4) using multiple grids you should increase also the relative cutoff  
> to really go at convergence.

Thansk for all the comments! I'll check the tests first.

best regards,


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