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Re^5: simultaneous bond scan

Jim Kress

Did you try running the Gradient extremals option?

$GRADEX group (optional, for RUNTYP=GRADEXTR)
This group controls the gradient extremal following
algorithm. The GEs leave stationary points parallel to
each of the normal modes of the hessian. Sometimes a GE
leaving a minimum will find a transition state, and thus
provides us with a way of finding that saddle point. GEs
have many unusual mathematical properties, and you should
be aware that they normally differ a great deal from IRCs.
The search will always be performed in cartesian
coordinates, but internal coordinates along the way may
be printed by the usual specification of NZVAR and $ZMAT.


On Sun Aug 29 '10 5:59am, Jonas Baltrusaitis wrote

>I will send you an email

>As to the symmetry, I am looking at every single opportunity and possibility in locating this TS as so far I have not been able to obtain even a ground state TS guess. After several manual constrained scans I always got TS guess with two negative frequencies and I still have not figured out what to do about that

>I acknowledge that thermal TS might be just very high in energy and only excited state TS will have reasonable structure. But, again, I have not been able to get a clean guess for TS so thought that symmetry might speed up my calculations to begin with

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