Dear Altruist,

I am running some QMMM jobs for finding the transition state and later on I want to do the IRC calculation if i can find the transition state.For me it is now a big problem to locate the transition state and to do the frequency calculation.The system has two layers.High layer I mean the quantum part contains the Adenosyl cobalamin cofactor and the low layer contains EAL enzyme.So the high layer contains 180 atoms which is treated by QM and the low layer contains 10000 atoms which is treated by MM.I am not sure is it possible to do the IRC calculation using gaussain for this type of big system.If anyone can give me some suggestions it would be a great help.

Thanks,

Mamun