Re: CCL:Transition state optimization



 hello,
 
In many cases a guess structure based on chemical intuition will optimize smoothly to a TS, especially at the AM1 or PM3 level. This semiempirical TS structure then usually serves as a good input for a higher-level job (initiating the TS opt with a semiempirical hessian).
 What is the reaction whose TS you want?
 EL
 ====
 Ramon Crehuet wrote:
 
 Dear Anne,
    If you know reactant and product structures, the NEB method:
 http://www-theory.chem.washington.edu/~graeme/research/neb/neb.html
 http://www-theory.chem.washington.edu/~graeme/research/docs/review.pdf
 or the LUP method, by Elber's Group can be useful.
 They are implemented in some Molecular Dynamics software (i.e. CHARMM).
 Best regards,
 Ramon Crehuet
 annek:at:chem.au.dk wrote:
 
 Does anyone have a suggestion to how I could perform a transition state
 
optimisation on a bimolecular system. I have tried the qst-method in Gaussian with now succes. Propably because my optimized reagtants differs to much from the structure of the products? To perform qst3 calculation I need an initial guess for the transition struture. Is there any general /computational) way to
 find such a structure??
 Anne Kjaersgaard
 Denmark
 
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