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x=0: diagonal guess (default) | x=0: diagonal guess (default for MO-TDDFT and AO-TDDFT under Abelian point groups) |
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x=2: tight-binding guess (usually much better than the diagonal guess). This also invokes a tight-binding preconditioner. | x=2: tight-binding guess (default for AO-TDDFT under Abelian point groups, usually much better than the diagonal guess). This also invokes a tight-binding preconditioner. |
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=== iwindow === The excitation energy window in which excited states are to be calculated. Two numbers must be provided in the next line, followed by an optional unit (au/eV/nm/cm-1). For example, {{{ iwindow 300 700 nm }}} specifies that all excited states within 300 nm and 700 nm are to be calculated. If no unit is given, the default unit is eV. When the Davidson diagonalization method is used, the calculated excited states are neither guaranteed to include all excited states within the window, nor guaranteed to be all contained in the window. To ensure that all and only those excited states within the window are calculated, the iVI method must be used: {{{ idiag 3 iviop 1 iwindow 300 700 nm }}} where "iviop 1" specifies that internal roots, rather than external roots, are requested. |
tddft: time-dependent density functional theory
Contents
-
tddft: time-dependent density functional theory
- Quick guides
- General keywords
- Convergence threshold
- States specification
- Save eigenvectors
- output eigenvector control
- TD-DFT/SOC and Property evaluation
- Stability analysis
- memory control
- Others
- Modified Davidson algorithm
- AO-TDDFT and AO-TDA
- Frozen orbital
- Spin-flip Kernel
- Some uncommon keywords just for testing methods
Time dependent DFT/HF calculation. Support Full TDDFT, TDA and RPA.
Quick guides
The following examples give the minimal inputs for starting TD-DFT calculations.
1. Closed-shell Systems : R-TD-DFT
2. Open-shell Systems : U-TD-DFT and spin-adapted TD-DFT for spin-conserving excitations
3. TD-DFT with spin-flip calculations
4. Open-shell Systems : Spin-flip TD-DFT for spin-flip excitations
6. TD-DFT with SOC: open-shell systems
7. TD-DFT with SOC: Kramers pairs
8. Excitation analyze based on molecular fragments
9. Nto analyze
General keywords
imethod
imethod 1, R-TDDFT, start from RKS imethod 2, U-TDDFT, start from UKS or ROKS imethod 3, X-TDDFT, start from ROKS (deprecated; please use imethod=2, itest=1 and icorrect=1 for X-TDDFT, vide infra)
isf
Spin flip TDDFT. isf 0, do not flip isf 1, spin flip up isf -1, spin flip down
itda
itda 0, TDDFT, do not use TDA itda 1, TDA
ialda
ialda=0: full non-collinear kernel (default; recommended for spin-conserving TD-DFT) ialda=1: non-collinear ALDA kernel ialda=2: non-collinear ALDA0 kernel (recommended for spin-flip TD-DFT) ialda=3: full non-collinear kernel but computed from spin-averaged density ialda=4: full collinear kernel (mandatory for spin-flip TD-DFT gradient and NAC)
itest,icorrect
itest=1;icorrect=1 must be setted for X-TD-DFT using the U-TD-DFT subroutines.
itrans
itrans=1: transform the final eigenvector in U-TD-DFT from the spin-orbital based representation to spin-adapted basis, e.g., CV(0) and CV(1). This only makes sense when ROKS reference is used.
iact,elw,eup
iact = 1: define active space based on energy [elw,eup]
elw: lower bound in eV (not in au!).
eup: upper bound in eV.
idiag
idiag=1: iterative, =2 full diag, =3 iVI diag (TDA and AO-TDDFT supported)
ndiag
aokxc
iguess
iguess=10*x+y
x=0: diagonal guess (default for MO-TDDFT and AO-TDDFT under Abelian point groups) x=1: read guess from file (iVI only, useful for restarting a failed calculation) x=2: tight-binding guess (default for AO-TDDFT under Abelian point groups, usually much better than the diagonal guess). This also invokes a tight-binding preconditioner. y=0: do not save eigenvectors during the TD-DFT iterations (default) y=1: save eigenvectors at each iteration (iVI only)
Convergence threshold
crit_e
crit_vec
States specification
iroot,iexit
The number of calculated excited states of each irreducible representation. If there are several irreps for a point group as C2v, iroot states will be calculated for each irreps. Use "iroot" instead of "iexit". "iexit" will be deleted in the future. For example,
# assume H2O molecule with C2v symmetry $tddft iroot 4 # totally 16 roots, 4 roots for A1, A2, B1, B2 irreps $end
nroot, nexit
Same as above, but different numbers can be specified for different irreps. Use nroot instead of nexit. For example:
# assume H2O molecule with C2v symmetry $tddft nroot 2 3 1 4 # irrep A1 - 2 roots; A2 - 3 roots; B1 - 1 root; B2 - 4 roots $end
iwindow
The excitation energy window in which excited states are to be calculated. Two numbers must be provided in the next line, followed by an optional unit (au/eV/nm/cm-1). For example,
iwindow 300 700 nm
specifies that all excited states within 300 nm and 700 nm are to be calculated. If no unit is given, the default unit is eV. When the Davidson diagonalization method is used, the calculated excited states are neither guaranteed to include all excited states within the window, nor guaranteed to be all contained in the window. To ensure that all and only those excited states within the window are calculated, the iVI method must be used:
idiag 3 iviop 1 iwindow 300 700 nm
where "iviop 1" specifies that internal roots, rather than external roots, are requested.
Save eigenvectors
istore
Integer: specify the file no. to store TDDFT information
lefteig
By default, in TD-DFT the left eigenvector X-Y is also stored.
output eigenvector control
nprt
cthrd
TD-DFT/SOC and Property evaluation
nfiles
No. of TD-DFT calculations to be loaded.
isoc
=1, Only work for closed-shell case (NOT recommended!)
=2, General SOC state interaction
=3, just print SOC matrix elements between two spin-free states (without diagonalization Hsoc).
ifgs
=0, default for not including ground state (GS) in SOC treatment; =1, include GS.
imatsoc
Define SOC matrices need to be calculated. Input format looks like
... #SCF calculation for the ground state S0. It is a singlet. $scf spin 0 ... $end #First TDDFT, singlets S0-S9. $tddft imethod 1 isf 0 iext 10 .... $end #Second TDDFT, triplet T1-T10 $tddft imethod 1 isf 1 iexit 10 $end $tddft .... imatsoc 7 0 0 0 2 1 1 0 0 0 2 1 2 1 1 1 2 1 1 1 1 1 2 1 2 1 1 2 2 1 1 1 1 2 2 1 2 2 1 1 2 1 1 2 1 1 2 1 2 $end
In this input, 7 means seven of SOC matrices will be calculate (If the number <0, then ALL possible HSOC mat will be printed !). Here, it is very tricky to specify states:
- The string "0 0 0" always treat as the ground state.
For other states, three numbers "n m n" represent "ith-tddft", "symmetry" and "ithstate" respectively. Therefore, the first matrix element "0 0 0 2 1 1" means SOC matrix of <S0|HSOC|T1>. The third matrix element "1 1 1 2 1 1" means SOC matrix <S1|HSOC|T1>. Here, the first "1" in bra state "1 1 1" means the state from first TDDFT calculation. The second and third "1" in the bra state "1 1 1" means this state has spatial symmetry "1" and is the first excited state.
imatrsf
Transition dipole between Spin-free states. The input is similar to imatsoc (but currently selected printing is not implemented). Simply use -1 to print all of them.
imatrso
Define transition dipole moment need to be printed between two SOC-included states. Input format looks like(notice we omit other input in TDDFT module)
$TDDFT ... imatrso 5 1 1 1 2 1 3 1 4 1 5 ... $END
Then, "imatrso" is specified to define transition dipole moments need to be printed. The number "5" require transition dipoles between 5-pairs of states to be print. The following 5 lines define which pairs will be printed. Here, we require transition dipoles between the first state and five states are printed.
imatnso
imatnsf
idiag
By default, idiag=0 uses full diagonalization (preferred for small model space).
If idiag=1, then TD-DFT/SOC can use Davidson's algorithm also, along with a specification for the no. of states by iexit.
iact
=1, allows to use active space specification for the projected active-orbital SOC Hamiltonian (P*HSOC*P), eup can be specified in (eV) to give a cut off to define active physically interested excited states.
ntoanalyze
Natural transition orbital analyze.
ntoanalyze 2 # number of states 1 3 # list of states in NTO analyze.
Stability analysis
isab
isave
memory control
memjkop
specific memory usage for ao-JK calculation (PER THREAD for imemshrink = 0)
imemshrink
imemshrink = 0: default
imemshrink = 1: reduce openmp memory usage for ao-JK and ao-Kxc calculation. Will be slower due to thread lock.
Others
isgn
ivo
Modified Davidson algorithm
Eneshift
Specify an energy window. States with excitation energies close to input value will be calculate. The energy unit is eV.
$TDDFT Eneshift 9.0 ... $End
AO-TDDFT and AO-TDA
AO-TDDFT supports R-TDDFT, U-TDDFT, R-TDDFT-SF+1. The possible combinations are imethod=1, itda=0, isf=0 imethod=1, itda=0, isf=1 imethod=2, itda=0, isf=0 AO-TDA supports R-TDA,U-TDA, R-TDA-SF+1, R-TDA-SF-1, U-TDA-SF3. The possible combinations are imethod=1, itda=1, isf=0 imethod=1, itda=1, isf=1 imethod=2, itda=1, isf=0 imethod=2, itda=1, isf=-1 imethod=2, itda=1, isf=3
Frozen orbital
Frzorb
Only valid for C1 symmetry.
Frzorb 4 # number of orbital to be frozen 1 4 6 7 # orbital list
Frzcore
Frzcore 1 2 2 1 # number of core orbitals will be frozen in each irrep
Frzvirt
Frzvirt 2 2 2 2 # number of virtual orbitals will be frozen in each irrep
Spin-flip Kernel
kernelctrl
=0; (va-vb)*(rhoa-rhob)/( (rhoa-rhob)^2+thrdab)
=2; old version using 2nd order derivatives Only affect GGA spin-flip TDDFT with ALDA0
thrdab
threshold for |rhoa-rhob|
Some uncommon keywords just for testing methods
idrpa
ispa
iro
icv
ioo