Molcas Forum

maheshg

Member

Registered: 2018-09-25

Posts: 9

Minimum energy path from S1 minimum to S1/S0 MECI

Dear All,

I have obtained S1/S0 minimum energy conical intersection as well as the S1 optimized geometry. Now I want to estimate the barrier for the path from S1_min to S1/S0 CI.

Would mep-search starting from the S1_min geometry directly reaches to the S1/S0?

Since the starting geometry is not the transition state, which direction will be considered as the reaction coordinate for the MEP calculation?

Any help regarding this would be highly appreciated.

Thank you
Mahesh

Ignacio

Administrator

From: Uppsala

Registered: 2015-11-03

Posts: 1,085

Re: Minimum energy path from S1 minimum to S1/S0 MECI

A MEP search from S1_min will lead nowhere, as it is already a minimum, it will just stay there.

To estimate the barrier you could perform some kind of geometry interpolation (for this you'd need external tools) between S1_min and S1/S0, that should give you at least an upper bound. More rigorously, you'd have to find a saddle point (TS) that connects S1_min and S1/S0 and run an IRC from there, but you'd probably reach some other CI point, and not the MECI.