Dear all,

I wonder if I can use EOM-CCSD to calculate the frequency of excited state (numerically)?

Thank you very much.

Best wishes

Dear all,

I wonder if I can use EOM-CCSD to calculate the frequency of excited state (numerically)?

Thank you very much.

Best wishes

EOM-CCSD is designed to calculate the energy difference between a converged CCSD solution and other states, so yes, it can calculate the frequency of *a transition between states*. If you mean something else by frequency, you’ll need to elaborate.

Dear jmisiewica,

Thank you very much for your help. In term of the frequency, I mean the vibrational analysis for the excited state, not the “intensity” or so.

Thank you very much.

In principle, yes. You can start from this input file, discard after line 17, and then swap “frequencies” for “geometry.” You will probably want to optimize on the excited state first.

*That said*, please try to run the computation before taking what I said at face value. I’m not sure if this has been done before, which makes me wary of possible bugs.

Thank you very much!

Best wishes