State-Averaged CASSCF with Symmetry


Dear all,

is it possible in Psi4 to perform a state-averaged CASSCF calculation for states having different symmetries? For example, how could I exemplary proceed, if I want to compute the ${}^3P$ ground state of a carbon atom?

Of course, I could perform a calculation in $C_1$ (see below), but this is a delicate task for larger systems.

molecule c {
0 3
symmetry c1

set {
basis cc-pVDZ
reference rohf
frozen_docc [2]
active [3]

set detci {
num_roots 3
avg_states [1,2,3]

casscf_energy = energy(‘casscf’)


Unfortunately this is not currently supported within Psi4.

While this is feasible, quite a few technical challenges would need to be overcome to make this possible. This has been requested before so we may explore this option in the future.


Has there been any progress on this issue? It would be very useful if Psi4 was able to average states across irreducible representations…


@sherrill Any thoughts here?