Gallium Excitations

[Sulstice]

Hi,

I have a molecule that has Gallium ion approaching the surface of an aromatic ring. There are 3 in the structure. I want to perform UV excitation on them to get an initial wavelength but running into problems.

Is my error so far. My code looks something like this:

psi4.set_options({
  'scf_type': 'df',
  'g_convergence': 'gau',
  'freeze_core': 'true',
  'reference': 'uhf',
  'save_jk': True,
  'fail_on_maxiter': 'false'
})

molecule = 'X'

energy, wave_function = psi4.energy(
       'hf/6-311g',
        return_wfn=True,
        molecule=self.molecule
)

rpa = tdscf_excitations(wave_function, states=[10])
poles = [r["EXCITATION ENERGY"] for r in rpa]
opa_residues = [np.linalg.norm(r["ELECTRIC DIPOLE TRANSITION MOMENT (LEN)"])**2 for r in rpa]
ecd_residues = [r["ROTATORY STRENGTH (LEN)"] for r in rpa]
opa_spectrum = spectrum(poles=poles, residues=opa_residues, gamma=0.01, out_units="nm")

Stacktrace Error:

  File "/home/sulstice/software/miniconda2/envs/qmpython3/lib/python3.9/site-packages/psi4/driver/procrouting/response/scf_response.py", line 720, in tdscf_excitations
    res_1 = _solve_loop(wfn, ptype, solve_function, singlets_per_irrep, maxiter, restricted, "singlet")
  File "/home/sulstice/software/miniconda2/envs/qmpython3/lib/python3.9/site-packages/psi4/driver/procrouting/response/scf_response.py", line 326, in _solve_loop
    ret = solve_function(engine, nstates, guess_, maxiter)
  File "/home/sulstice/software/miniconda2/envs/qmpython3/lib/python3.9/site-packages/psi4/driver/procrouting/response/scf_response.py", line 690, in rpa_solver
    return solvers.hamiltonian_solver(engine=e,
  File "/home/sulstice/software/miniconda2/envs/qmpython3/lib/python3.9/site-packages/psi4/driver/p4util/solvers.py", line 989, in hamiltonian_solver
    raise RuntimeError(msg)
RuntimeError: The H2 matrix is not Positive Definite. This means the reference state is not stable.

Running things I would maybe predict at UHF is not right and I don't think this is a coordinate optimization problem. Or what do y'all think?