PSI4 version: 1.4rc1
I am attempting to generate singlet and triplet excitations with TD-DFT. The following minimal input gives me an error:
molecule {
N
N 1 1
}
set {
reference RHF
TDSCF_States [10]
TDSCF_Triplets also
}
energy('td-BP86/6-31G*')
TDSCF: Restricted Vx kernel only spin-adapted for singlets
When I attempt to use a UHF reference, I get the following error:
TDSCF: Cannot compute triplets with an unrestricted reference
The only way I can get it to run is if I switch from DFT to SCF. Is there a way to perform triplet excitations with TD-DFT in PSI4, or do I need to add additional keyword(s)?