[CP2K:6828] SCF convergence in NEB calculation

hut... at chem.uzh.ch hut... at chem.uzh.ch
Wed Jul 29 09:33:32 CEST 2015


Hi Tobias

I would start using a very conservative setting for the SCF
optimizer. For example

    &SCF
      MAX_SCF 20
      SCF_GUESS ATOMIC
      EPS_SCF  1.e-06
      &OT ON
        MINIMIZER CG
        ENERGY_GAP 0.002
        LINESEARCH 3PNT
        PRECONDITIONER FULL_ALL
      &END OT
      &OUTER_SCF
        MAX_SCF 20
        EPS_SCF  1.e-06
      &END OUTER_SCF
    &END SCF

But maybe you already do this?

Juerg

--------------------------------------------------------------
Juerg Hutter                         Phone : ++41 44 635 4491
Institut für Chemie C                FAX   : ++41 44 635 6838
Universität Zürich                   E-mail: hut... at chem.uzh.ch
Winterthurerstrasse 190
CH-8057 Zürich, Switzerland
---------------------------------------------------------------

-----cp... at googlegroups.com wrote: -----To: cp2k <cp... at googlegroups.com>
From: Tobias Kraemer <161brun... at gmail.com>
Sent by: cp... at googlegroups.com
Date: 07/28/2015 12:44PM
Subject: [CP2K:6828] SCF convergence in NEB calculation

Hi all,


I am running CI-NEB calculations in order to locate transition states along a reaction profile involving organometallic species in the solid state. More precisely, this is a hydrogenation reaction of double bonds, i.e. addition of H2 to an alkene. This should be a straightforward task. Anyway, for some cases it seems the SCF encounters problems to converge, or converges to the wrong electronic state. In particular, those replicas are affected which lead to the  transition
 state. I can see that the electronic structure may be a bit tricky, 
since in a TS notable rearrangement of the electrons takes place. It goes without saying, that having a wrong electronic structure in the TS leads to unreasonably high barriers. I should add that these type of calculations haven't imposed any problems so far using other codes. What causes some additional puzzlement is the fact that for the same TS search slightly different input  geometries lead to very different behaviour of the SCF. In one case there is reasonable convergence to a decent electronic structure, in the other case the SCF goes completely havoc.  

So my question really is, how can I control the SCF convergence for a particular replica? Can this be done in the main input file?

your comments are appreciated


Tobi





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