[Wien] Transition-State/NEB Calculations

[Víctor Luaña Cabal]

* Laurence Marks <L-marks at northwestern.edu> [2018-06-15 08:19:30 -0500]:
> Dear Victor,
> 
> Thanks for the email. The very specific question I am asking is whether it
> is "well known" with Vasp, Ab-init, Gaussian etc that one needs "good"
> parameters such as k-mesh etc for the transition state. I am hoping that
> there are people who have done NEB (for instance) calculations on this
> mailing list.

Laurence,

Let me go back to the subject. The method finally working in molecular
codes is best thna NEB and it is based in the idea that coming to a TS
the surface profile of a minimum changes into a transition state ;-)
That means that, if you are looking for a first-order transition state
(the one involved in most reactions), one of the eigenvalues of the
hessian matrix changes sign.

The solution prefered in most molecular codes consist in modifying
artificially the sign of the incumbent eigenvalue and converting the
problem into a false minimum exploration.

You can find an old code implementing this idea in navigator
<http://azufre.quimica.uniovi.es/software.html#navigator>, an in-house
code never published. The idea of navigator, optim and derive is making
available the algorithms and being able to use data comming from every
kind of electronic code you may have at hand.

Let me invite you to examine
<http://azufre.quimica.uniovi.es/software.html> in our web page
<http://azufre.quimica.uniovi.es/>, Maybe you find it useful.

On a different subject I was thinking into organizing a CECAM
worshop/school on "computer tools for computational scientists" and my
idea was showing the students how computational science is created.
Might this issue interest you? We don't need bothering the wien2k
list and you have my email at the signature.

Cheers,
       Víctor Luaña
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