The computation of Hartree-Fock excitation energies and length gauge oscillator strengths are currently available for restricted HF and QED-HF. A description of how to perform generic HF and QED-HF calculations are given in the Hartree-Fock calculation and QED-HF calculation tutorial. In addition to the sections that are needed for a ground state HF or QED-HF calculation, the tdhf excited state keyword must be specified in the do section:
- do
tdhf excited state
Furthermore, you must add the solver hf es section and specify the number of singlet states, for instance:
- solver tdhf es
singlet states: 2
In this same section you can specify, among other keywords, the restart, max iterations, tamm-dancoff and threshold keywords.
The rotatory strength and oscillator strengths in velocity and mixed gauge can be computed using the keywords dipole velocity and rotatory strength
in the hf reponse section.
A minimal working example is:
- do
tdhf excited state
- memory
available: 8
- method
hf
- solver tdhf es
singlet states: 2
- geometry
basis: cc-pVDZ
H 0.8475370000 0.0347360000 1.0345270000
C 0.3504820000 0.0067450000 0.0608350000
H 0.6350750000 0.8927640000 -0.5200650000
H 0.6629360000 -0.8933800000 -0.4828330000
O -1.0108350000 -0.0082340000 0.3643870000
H -1.4851950000 -0.0326310000 -0.4568520000
If successful, you should find a summary of the excitation energies, transition moments and oscillator strengths at the end of the output file:
- TDHF excitation energies:
Excitation energy
------------------------------------------
State (Hartree) (eV)
---------------------------------------------------------------
1 0.330048904040 8.981088133311
2 0.406144230368 11.051747432337
---------------------------------------------------------------
eV/Hartree (CODATA 2014): 27.21138602
- Summary of TDHF transition properties calculation:
States m = 0 and n = 1:
-------------------------
Excitation energy [E_h]: 0.330048904040
Excitation energy [eV]: 8.981088133311
Transition moments [a.u.] Transition strength [a.u.]
------------------------------------------------------------------
Comp. <m|r|n> |<m|r|n>|^2
------------------------------------------------------------------
X 0.0003509311 0.0000001232
Y -0.0227066964 0.0005155941
Z 0.0004825970 0.0000002329
------------------------------------------------------------------
Oscillator strength: 0.000113525847
States m = 0 and n = 2:
-------------------------
Excitation energy [E_h]: 0.406144230368
Excitation energy [eV]: 11.051747432337
Transition moments [a.u.] Transition strength [a.u.]
------------------------------------------------------------------
Comp. <m|r|n> |<m|r|n>|^2
------------------------------------------------------------------
X 0.0838600158 0.0070325022
Y -0.0015004221 0.0000022513
Z -0.1261278272 0.0159082288
------------------------------------------------------------------
Oscillator strength: 0.006212106595
For QED-HF we also provide an esitmation of the photon character of the excitation.