Dear All

Im studing reactions by DFT with gaussian (9 instead of 16).

Currently im performing IRC on my TS# . For the full serie, all of them show a interesting shape in the reverse path

1- decrease of energie

2- ~slow decrease that beacme moreorless flat depending on the substituant ob my reagent (EDG give something flat)

3-strong decrease of the energie connecting to the expecteed intermeadiate.

So far i succeded in performing them decreasing the step size (=3).

However for 2 of them (strongly donnating substituant) the irc stop in the middle of the ~flat part of the IRC,. It s still slighly decreasing but the RMN Gradient Norm became < 5.10^-5.

I try to add tight of decrease the step size. It change anything

-I also try to change the iop(1/7). It s eaver worth as far as the optimisation of every single point take ages.

Does somebody know how to change the RMS gradient Norm that command IRC to stop and not changing the optimisation parameter of every single point?

Thanks a lot

xof