[CP2K-user] [CP2K:10796] Transition state search with DIMER METHOD

luca lcb... at gmail.com
Wed Oct 3 14:39:04 CEST 2018


Hi Stefano,
the dimer method does not work like the Hessian-Newton-Raphson method
where the Hessian is evaluated at the beginning of the calculation etc.
DM follows the local curvature of the potential energy and the research
direction is locally evaluated at each research step, not just an
update. Therefore, it is not mandatory to know the geometry of the
reagents/products.
At the starting point it is not necessary to know the right "direction"
of the reaction, because DM is able to find it by itself.
These are the main features of the method!

NEB is not the right choice if you do not have a reliable starting/
ending point of the reaction. 
I do not know your experience, but DM is quite complex and I would
suggest reading the works of G. Henkelman
(http://theory.cm.utexas.edu/henkelman/research/saddle)

Bests,

L

On mer, 2018-10-03 at 12:59 +0200, Stefano Pantaleone wrote:
> Hi Luca,
> 
> thank you very much for you fast reply. This is quite strange for me.
> In my experience of TS search, it is mandatory to give to the
> algorithm the direction to follow along which the energy has to be
> maximize, otherwise the algorithm go to reactants of products. I do
> not have a good starting geometry; in this case I suppose the best
> way to proceed is a NEB. I preferred to avoid NEB because it is quite
> expensive, so I tried with DIMER.
> 
> Thank you very much,
> Stefano
> 
> Il giorno mer 3 ott 2018 alle ore 12:28 luca <lcb... at gmail.com> ha
> scritto:
> > Hi Stefano,
> > the starting orientation of the dimers is random,
> > so you have not to generate them. See "Section DIMER_VECTOR"
> > Anyway, usually if you do not have a very good starting point
> > geometry,
> > the random orientation is the best choice.
> >    
> > Luca
> > 
> > 
> > On mer, 2018-10-03 at 02:58 -0700, Stefano Pantaleone wrote:
> > > Hi everybody,
> > > 
> > > I am using the DIMER METHOD to search for a transition state, but
> > I
> > > do not understand how to generate the starting DIMER VECTOR, and
> > I do
> > > not find this information in any discussion. In other programs
> > this
> > > can be done with a previous frequency calculation, but if this is
> > > also the case I do not know how to print if from a VIBRATIONAL
> > > ANALYSIS.
> > > 
> > > Thank you in advance for your help,
> > > Stefano
> > > 
> > > 
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