How to get energies of all hartree-fock orbitals and energies of all CIS excitations from python interface.
could you be more precise what you mean with CIS excitations? excited state energies?
properties from the HF wavefunction you can get from this class:
wfn.epsilon_a() is a vector of alpha spin HF orbitals if you do a HF calculation.
Yes, energies of all CIS excited states are required.
The new TD-SCF code can give you CIS excitation energies if you use the TDA approximation with HF.
It is, however, only available in the development version.
You can find usage examples in the samples, e.g here https://github.com/psi4/psi4/blob/master/tests/tdscf-1/input.dat
The excitation energies are stored on the wfn object as shown.
Another option is to access the low-level tdscf driver that returns a dictionary that you can access:
from psi4.driver.procrouting.response.scf_response import tdscf_excitations e, wfn = psi4.energy(“HF/cc-pvdz”, return_wfn=True) res = tdscf_excitations(wfn, tda=True, states=N) # set desired states to calculate (N), can be a list for irreps. ene_ex = [r["EXCITATION ENERGY"] for r in res] # array of excitation energies