I’ve read that it was a goal to implement this for 1.4 and then for 1.5. And I saw on GitHub that there might be code for this in the developer version (psi4/vib.py at master · psi4/psi4 · GitHub, line e.g 417).
I tested to calculate the frequencies for one example using frequency(“b3lyp-d3bj”) using psi4 1.5, but besides the frequencies I did not seem to get any intensities.
Do I need to call or add something else in order to get the intensity information?
We have intensities for analytic frequencies. This is currently only available for closed-shell HF and LDA functionals, so not for B3LYP.
Intensities for frequencies by finite difference of analytic gradients are theoretically possible. It’s something we’ve wanted ever since 1.4, but it kept getting pushed back. This feature will be added for either the 1.6 release next month or the 1.7 release in November/December. I’ll have a better estimate on which of the two it will be, after Wednesday.
Intensities by finite difference of energies are not theoretically possible.
Ok, thank you for this information. I keep my fingers crossed that it will be added in 1.6! It would be very nice of you, if you could write here after Wednesday when the intensity calculation for frequencies by finite difference of analytic gradients is planned to be added.