State-Averaged CASSCF with Symmetry

#1

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
C
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’)

#2

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.

#3

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

#4

@sherrill Any thoughts here?