Pushing the transition state to minima in Dimer method

[ckande]

Hello there,

I am looking at hydrogen dissociation from CH4 on Ru0001 surface [(CH4(surf) -> CH3(surf) + H(surf)]. I calculated the transition state for the reaction using the dimer method starting from CH4(surf). I would like to know if it is now possible to push the transition state to CH3(surf) + H(surf). If yes, how can this be done?

A simple relaxation of the transition state might not guarantee that the reaction goes forward to CH3(surf) + H(surf), right? As far as I can understand, it can as well go back to CH4(surf). So, how do I bias the relaxation to go forward.

Thanks for any suggestions.

Regards,
Chai

[graeme]

You can make a small displacement forward and backwards along the negative mode at the saddle (along the dimer direction). Then a careful minimization should give you both initial and final state. If you only want one of these states, you can probably use some intuition to decide which direction at the saddle corresponds to which minimum.

There is even a little script to generate the initial displacements from a converged dimer run: dimmins.pl