The computation of Hartree-Fock excitation energies and 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
end do
Furthermore, you must add the solver tdhf es section and specify the number of singlet states, for instance:
solver tdhf es
singlet states: 2
end solver tdhf es
In this same section you can specify, among other keywords, the restart, max iterations, tamm-dancoff and threshold keywords.
A minimal working example is:
system
name: methanol
charge: 0
end system
do
tdhf excited state
end do
memory
available: 8
end memory
method
hf
end method
solver tdhf es
singlet states: 2
end solver tdhf es
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
end geometry
If successful, you should find a summary of the excitation energies, transition dipole 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. q <m|q|n> |<m|q|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. q <m|q|n> |<m|q|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.