Molcas Forum

sourav ghoshal

Member

Registered: 2017-09-21

Posts: 25

Difficult to locate Transition state for CASSCF

I am trying to locate transition state for S, O and H compound using CASSCF/cc-pVDZ calculation along with (9,9) active space.

I have successfully optimized/locate the TS using ORCA program.

Now, I want to do same thing in MOLCAS for calculating the CASPT2 single point energy.

However, I have failed several times to locate the Transition State in MOLCAS using 'TS' as well as 'FindTS' keywords.

Is there any other alternative options to locate the transition state along reaction path (Reactant complex -> TS -> Product complex)?

Is the molecule contains S, O and H is basis set sensitive? Can I get success by increase the basis set or active space?

My Molecule has one S atom, five Oxygen atoms and three H atoms.

Any help will be highly appreciated

Ignacio

Administrator

From: Uppsala

Registered: 2015-11-03

Posts: 1,085

Re: Difficult to locate Transition state for CASSCF

You could try the alternative "saddle" method.

sourav ghoshal

Member

Registered: 2017-09-21

Posts: 25

Re: Difficult to locate Transition state for CASSCF

I have run one calculation using RP-Coor method.

I have seen two separate files one for reactant (*.reac.geo.molden) and other for product (*.pdt.geo.molden).

Could you please tell me that how to further proceed to locate TS?

Ignacio

Administrator

From: Uppsala

Registered: 2015-11-03

Posts: 1,085

Re: Difficult to locate Transition state for CASSCF

Check the log file. If the optimization was successful, you should have the TS geometry near the end (and in the newest of those files). There should also be a .saddle.molden file with the TS somewhere in the middle (probably identifiable in an energy plot).