Using Psi4 for excited state optimization with root following

Dear colleagues, I am trying to run a relaxed scan on the first excited singlet and triplet for a series of organic molecules. It looks like due to a lot of state flipping it is important to have root following active.

Is it possible to do this calculation with Psi4?

I’m not an expert on excited-state optimization, so I’d need to check the particular method you want to use.

Given that these are organic molecules, am I correct that you’re wanting TD-DFT starting from a closed-shell system?

Yes, @jmisiewicz , TD-DFT should be enough.
Thank you very much.

It looks like the answer is “no.” I’ll file a feature request for this.

And just to be clear, what exactly do you mean by “state flipping”? Are you talking about two PES “crossing” (normally, this would be an avoided crossing), or something else?

Hi, Jonathon, thank you very much for looking at this, I’m looking forward for using Psi4 for excited state chemistry.

The state flipping that I was referring to is when, let’s say, during the optimization to the first excited state, during the optimization, as the geometry changes, the S1 state changes its position with another excited state. ORCA, Gaussian and NWChem have root (or state) following to keep track of such changes. Here is the Q-Chem implementation: 9.7.5 State-Tracking Algorithm‣ 9.7 Nonadiabatic Couplings and Optimization of Minimum-Energy Crossing Points ‣ Chapter 9 Exploring Potential Energy Surfaces: Searches for Critical Points and Molecular Dynamics ‣ Q-Chem 5.3 User’s Manual

Again, thanks for the great software.

Okay, yes, that’s what I thought, but glad we confirmed. I added an issue to add a feature like that, so it’s on our (admittedly long) to-do list.

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