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Re: optimization process and transition state

Alex Granovsky

Dear B. Koa,

this can be the indication that there is no transition state.
However, please take in mind that the default geometry optimization
code in Firefly try to avoid saddle points and their vicinities
by its design; and in most cases it is quite successful in doing this.

Thus, the saddle point can be still there but just was walked
around during geometry optimization. In most cases it is very
helpful to look at the graph of energy vs. optimization step;
e.g., using ChemCraft. Look at the flat regions somewhere at the
middle of the optimization process (if any), they can be close to
TS structures.
Finally, my guess is that for the process you are modeling,
the existence or absence of TS should depend on the level of
theory used in computations.

Alex Granovsky

On Mon Sep 20 '10 2:42pm, B. Koa wrote
>Dear Firefly Users

>When I optimized a "H2O2" molecule on a cluster surface, it dissociated to 2 "OH"s which adsorbed on the cluster through the optimization process. Through this optimization process by Firefly the scf energies decrease and finally the job completes. Now, Can I be sure that there is not any transition state for H2O2 dissociation here ? I appreciate your help in advance.

>Best Wishes
>B. Koa  

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