Ceilidh ... Re^3: IRC in DLCs with frozen atoms or coords

Firefly and PC GAMESS-related discussion club

Re^3: IRC in DLCs with frozen atoms or coords - is this possible?

Do you really need an IRC? To find a transition state, you may first try linear transit between the reagent and product states. Just perform a series of constrained optimizations along the line connecting the reagent and product minima. The maximum along this line will be a good guess for a transition state. Next, you may try to perform a TS search with some atoms frozen.

If you already have a TS, you may try linear transit from TS to both reagent and product valleys.

>Thanks for the answer!
>This is really sad... From one hand side, it's of course known that any geometry optimization with partially frozen coordinates will not lead to true extremum, the same is with IRC...
>But nevertheless, we do optimization as well as TS search freezing some atoms, so why don't do this in IRC? Anyway, if so, I should examine my hypotheses more thoroughly, perhaps the cluster became stable after its correction...
>

Wed Mar 23 '11 1:34am

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