Input for time-dependent density functional theory calculations follows very closely the input already described for the uncorrelated excited state methods described in the previous section (in particular, see Section 7.2.7). There are several points to be aware of:
The exchange and correlation functionals are specified exactly as for a ground state DFT calculation, through EXCHANGE and CORRELATION.
If RPA is set to TRUE, a “full” TDDFT calculation will be performed, however the default value is RPA = FALSE, which invokes the TDA,^{378} in which the de-excitation amplitudes $\mathbf{Y}$ in Eq. (7.15) are neglected, which is usually a good approximation for excitation energies, although oscillator strengths within the TDA no longer formally satisfy the Thomas-Reiche-Kuhn sum rule.^{152} For RPA = TRUE, a TDA calculation is performed first and used as the initial guess for the full TDDFT calculation. The TDA calculation can be skipped altogether using RPA = 2
If SPIN_FLIP is set to TRUE when performing a TDDFT calculation, a SF-DFT calculation will also be performed. At present, SF-DFT is only implemented within TDDFT/TDA so RPA must be set to FALSE. Remember to set the spin multiplicity to 3 for systems with an even-number of electrons (e.g., diradicals), and 4 for odd-number electron systems (e.g., triradicals).
TRNSS
Controls whether reduced single excitation space is used.
TYPE:
LOGICAL
DEFAULT:
FALSE
Use full excitation space.
OPTIONS:
TRUE
Use reduced excitation space.
RECOMMENDATION:
None
TRTYPE
Controls how reduced subspace is specified.
TYPE:
INTEGER
DEFAULT:
1
OPTIONS:
1
Select orbitals localized on a set of atoms.
2
Specify a set of orbitals.
3
Specify a set of occupied orbitals, include excitations to all virtual orbitals.
RECOMMENDATION:
None
N_SOL
Specifies number of atoms or orbitals in the $solute section.
TYPE:
INTEGER
DEFAULT:
No default.
OPTIONS:
User defined.
RECOMMENDATION:
None
CISTR_PRINT
Controls level of output.
TYPE:
LOGICAL
DEFAULT:
FALSE
Minimal output.
OPTIONS:
TRUE
Increase output level.
RECOMMENDATION:
None
CUTOCC
Specifies occupied orbital cutoff.
TYPE:
INTEGER
DEFAULT:
50
OPTIONS:
0-200
CUTOFF = CUTOCC/100
RECOMMENDATION:
None
CUTVIR
Specifies virtual orbital cutoff.
TYPE:
INTEGER
DEFAULT:
0
No truncation
OPTIONS:
0-100
CUTOFF = CUTVIR/100
RECOMMENDATION:
None
PBHT_ANALYSIS
Controls whether overlap analysis of electronic excitations is performed.
TYPE:
LOGICAL
DEFAULT:
FALSE
OPTIONS:
FALSE
Do not perform overlap analysis.
TRUE
Perform overlap analysis.
RECOMMENDATION:
None
PBHT_FINE
Increases accuracy of overlap analysis.
TYPE:
LOGICAL
DEFAULT:
FALSE
OPTIONS:
FALSE
TRUE
Increase accuracy of overlap analysis.
RECOMMENDATION:
None
SRC_DFT
Selects form of the short-range corrected functional.
TYPE:
INTEGER
DEFAULT:
No default
OPTIONS:
1
SRC1 functional.
2
SRC2 functional.
RECOMMENDATION:
None
OMEGA
Sets the Coulomb attenuation parameter for the short-range component.
TYPE:
INTEGER
DEFAULT:
No default
OPTIONS:
$n$
Corresponding to $\omega =n/1000$, in units of bohr${}^{-1}$
RECOMMENDATION:
None
OMEGA2
Sets the Coulomb attenuation parameter for the long-range component.
TYPE:
INTEGER
DEFAULT:
No default
OPTIONS:
$n$
Corresponding to $\omega 2=n/1000$, in units of bohr${}^{-1}$
RECOMMENDATION:
None
HF_SR
Sets the fraction of Hartree-Fock exchange at ${r}_{12}=0$.
TYPE:
INTEGER
DEFAULT:
No default
OPTIONS:
$n$
Corresponding to HF_SR = $n/1000$
RECOMMENDATION:
None
HF_LR
Sets the fraction of Hartree-Fock exchange at ${r}_{12}=\mathrm{\infty}$.
TYPE:
INTEGER
DEFAULT:
No default
OPTIONS:
$n$
Corresponding to HF_LR = $n/1000$
RECOMMENDATION:
None
WANG_ZIEGLER_KERNEL
Controls whether to use the Wang-Ziegler non-collinear exchange-correlation
kernel in a SF-DFT calculation.
TYPE:
LOGICAL
DEFAULT:
FALSE
OPTIONS:
FALSE
Do not use non-collinear kernel.
TRUE
Use non-collinear kernel.
RECOMMENDATION:
None