[CP2K-user] how to improve energy convergence parameters for water molecule in gapw

[pavan kumar behara]

 Hello CP2K developers,

I am using CP2K-6.1 and performed HF energy calculation for water molecule
using GAPW method with an all electron basis. I used UHF for the run. When
I use the same basis set and do the same calculation with Gamess package
(using spherical harmonics), I observed energy differences of the order of
1E-04 with CP2K. I encountered similar issue before for atoms and
increasing the size of atomic grids (lebedev and radial) and tightening
convergence parameters solved it
<https://groups.google.com/d/topic/cp2k/_jmKkh9lS0s/discussion>. Even with
tighter convergence I am getting a slight mismatch for water molecule
calculation. It was mentioned in an earlier post
<https://groups.google.com/d/topic/cp2k/RUFQScjSDn0/discussion> that it is
common to observe energy differences in few microhartree for small
molecules with GAPW method. Is it okay to ignore this small difference or
is there a chance to improve my calculation?

Energy in a.u.
CP2K -76.01997566
GAMESS -76.02037291
difference 0.000397257

I attached all the inputs and outputs for cp2k as well as gamess for your
reference.

Thank you very much for your time, any help is appreciated.


Best regards,
Pavan.
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