I’m able to calculate IR intensities for SCF, but not for DFT. Is there something I’m missing, or has this just not been implemented for DFT?

Probably a bit of both.

My *suspicion* is that the RHF cases have analytic hessians, where the DFT cases have a finite difference of analytic gradients. All the information to compute the IR intensities (within the electrical harmonicity approximation) is in the finite difference of analytic gradients, but we don’t compute them at present. This was originally going to be a 1.4 target, but that’s coming in with the “recursive driver,” which has been moved to 1.5.

I believe that DFT does not have an analytic hessian in PSI4, so I guess I’m out of luck. Thanks for the information, I guess I’ll look into a different program.