SCF convergence in NEB calculation

Tobias Kraemer 161brun... at
Tue Jul 28 10:44:17 UTC 2015

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


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