Example: Subsystem TDDFT, coupled FDE excitation energies¶
This is example for coupled FDE calculation of excitation energies. The subsystem TDDFT code couples the monomer excitations to obtain the excited states of the total system (often denoted as coupled frozen density embedding, FDEc).
First the isolated fragments are calculated, the TAPe21’s of these fragments are t21.iso.rho1 and t21.iso.rho2. Next uncoupled FDE excitation energies are calculated in which one fragment is frozen and the other active. The key ALLOW PARTIALSUPERFRAGS is necessary to be able to use subsystem information for only one subsystem from a TAPE21 file of a previous FDE calculation.
$ADFBIN/adf << eor
Title Fragment no. 1; relaxed
SYMMETRY NOSYM
XC
GGA BECKE88 PERDEW86
END
EXCITATION
ONLYSING
LOWEST 20
CDSPECTRUM
ANALYTIC
VELOCITY
END
ALLOW PARTIALSUPERFRAGS
FRAGMENTS
rho1 t21.iso.rho1 subfrag=active
rho2 t21.iso.rho2 subfrag=active type=fde
END
ATOMS
1 C 1.05754858422573 -1.70701086799077 -3.50 f=rho1
2 O 2.28164544472573 -1.70701086799077 -3.50 f=rho1
3 C 0.20221626882573 -0.49944933059077 -3.50 f=rho1
4 H 0.49106545372573 -2.67285236319077 -3.50 f=rho1
5 C -1.19491351307427 -0.64892031589077 -3.50 f=rho1
6 C 0.76942690052573 0.78743686120923 -3.50 f=rho1
7 C -2.02186702237427 0.47538393990923 -3.50 f=rho1
8 H -1.62606655117427 -1.65281003349077 -3.50 f=rho1
9 C -0.05719256647427 1.90851291410923 -3.50 f=rho1
10 H 1.85606600152573 0.87752625020923 -3.50 f=rho1
11 C -1.45186603427427 1.75322106580923 -3.50 f=rho1
12 H -3.10608163477427 0.35931991730923 -3.50 f=rho1
13 H 0.37787441672573 2.90894982040923 -3.50 f=rho1
14 H -2.09570824397427 2.63406412680923 -3.50 f=rho1
15 C 2.00708906832899 0.06235850568037 3.50 f=rho2
16 O 2.61913749857899 1.12245748356614 3.50 f=rho2
17 C 0.53364394260760 -0.07460023943380 3.50 f=rho2
18 H 2.56029077395134 -0.91115102374797 3.50 f=rho2
19 C -0.03547527794391 -1.35928561559301 3.50 f=rho2
20 C -0.29722687542061 1.06006167281502 3.50 f=rho2
21 C -1.42262807969967 -1.51329623449550 3.50 f=rho2
22 H 0.61834220104568 -2.23461995830645 3.50 f=rho2
23 C -1.68141695030640 0.90472624158027 3.50 f=rho2
24 H 0.16807297559397 2.04616343352651 3.50 f=rho2
25 C -2.24426699857796 -0.38074233566867 3.50 f=rho2
26 H -1.86422099386266 -2.51028564328820 3.50 f=rho2
27 H -2.33028723444571 1.78172375452933 3.50 f=rho2
28 H -3.32902057100121 -0.49790451479758 3.50 f=rho2
END
FDE
PW91K
END
END INPUT
eor
mv TAPE21 t21.emb.rho1
$ADFBIN/adf << eor
Title Fragment no. 2; relaxed
SYMMETRY NOSYM
XC
GGA BECKE88 PERDEW86
END
EXCITATION
ONLYSING
LOWEST 20
CDSPECTRUM
ANALYTIC
VELOCITY
END
ALLOW PARTIALSUPERFRAGS
FRAGMENTS
rho1 t21.emb.rho1 subfrag=active type=fde
rho2 t21.iso.rho2 subfrag=active
END
ATOMS
1 C 1.05754858422573 -1.70701086799077 -3.50 f=rho1
2 O 2.28164544472573 -1.70701086799077 -3.50 f=rho1
3 C 0.20221626882573 -0.49944933059077 -3.50 f=rho1
4 H 0.49106545372573 -2.67285236319077 -3.50 f=rho1
5 C -1.19491351307427 -0.64892031589077 -3.50 f=rho1
6 C 0.76942690052573 0.78743686120923 -3.50 f=rho1
7 C -2.02186702237427 0.47538393990923 -3.50 f=rho1
8 H -1.62606655117427 -1.65281003349077 -3.50 f=rho1
9 C -0.05719256647427 1.90851291410923 -3.50 f=rho1
10 H 1.85606600152573 0.87752625020923 -3.50 f=rho1
11 C -1.45186603427427 1.75322106580923 -3.50 f=rho1
12 H -3.10608163477427 0.35931991730923 -3.50 f=rho1
13 H 0.37787441672573 2.90894982040923 -3.50 f=rho1
14 H -2.09570824397427 2.63406412680923 -3.50 f=rho1
15 C 2.00708906832899 0.06235850568037 3.50 f=rho2
16 O 2.61913749857899 1.12245748356614 3.50 f=rho2
17 C 0.53364394260760 -0.07460023943380 3.50 f=rho2
18 H 2.56029077395134 -0.91115102374797 3.50 f=rho2
19 C -0.03547527794391 -1.35928561559301 3.50 f=rho2
20 C -0.29722687542061 1.06006167281502 3.50 f=rho2
21 C -1.42262807969967 -1.51329623449550 3.50 f=rho2
22 H 0.61834220104568 -2.23461995830645 3.50 f=rho2
23 C -1.68141695030640 0.90472624158027 3.50 f=rho2
24 H 0.16807297559397 2.04616343352651 3.50 f=rho2
25 C -2.24426699857796 -0.38074233566867 3.50 f=rho2
26 H -1.86422099386266 -2.51028564328820 3.50 f=rho2
27 H -2.33028723444571 1.78172375452933 3.50 f=rho2
28 H -3.32902057100121 -0.49790451479758 3.50 f=rho2
END
FDE
PW91K
END
END INPUT
eor
mv TAPE21 t21.emb.rho2
Finally a calculation in which the excitation energies may couple, using the SUBEXCI block keyword.
$ADFBIN/adf << eor
Title COUPLED SUBSYSTEM EXCITATIONS
SYMMETRY NOSYM
XC
GGA BECKE88 PERDEW86
END
DIFFUSE
ALLOW PARTIALSUPERFRAGS
FRAGMENTS
rho1 t21.emb.rho1 subfrag=active
rho2 t21.emb.rho2 subfrag=active type=fde
END
ATOMS
1 C 1.05754858422573 -1.70701086799077 -3.50 f=rho1
2 O 2.28164544472573 -1.70701086799077 -3.50 f=rho1
3 C 0.20221626882573 -0.49944933059077 -3.50 f=rho1
4 H 0.49106545372573 -2.67285236319077 -3.50 f=rho1
5 C -1.19491351307427 -0.64892031589077 -3.50 f=rho1
6 C 0.76942690052573 0.78743686120923 -3.50 f=rho1
7 C -2.02186702237427 0.47538393990923 -3.50 f=rho1
8 H -1.62606655117427 -1.65281003349077 -3.50 f=rho1
9 C -0.05719256647427 1.90851291410923 -3.50 f=rho1
10 H 1.85606600152573 0.87752625020923 -3.50 f=rho1
11 C -1.45186603427427 1.75322106580923 -3.50 f=rho1
12 H -3.10608163477427 0.35931991730923 -3.50 f=rho1
13 H 0.37787441672573 2.90894982040923 -3.50 f=rho1
14 H -2.09570824397427 2.63406412680923 -3.50 f=rho1
15 C 2.00708906832899 0.06235850568037 3.50 f=rho2
16 O 2.61913749857899 1.12245748356614 3.50 f=rho2
17 C 0.53364394260760 -0.07460023943380 3.50 f=rho2
18 H 2.56029077395134 -0.91115102374797 3.50 f=rho2
19 C -0.03547527794391 -1.35928561559301 3.50 f=rho2
20 C -0.29722687542061 1.06006167281502 3.50 f=rho2
21 C -1.42262807969967 -1.51329623449550 3.50 f=rho2
22 H 0.61834220104568 -2.23461995830645 3.50 f=rho2
23 C -1.68141695030640 0.90472624158027 3.50 f=rho2
24 H 0.16807297559397 2.04616343352651 3.50 f=rho2
25 C -2.24426699857796 -0.38074233566867 3.50 f=rho2
26 H -1.86422099386266 -2.51028564328820 3.50 f=rho2
27 H -2.33028723444571 1.78172375452933 3.50 f=rho2
28 H -3.32902057100121 -0.49790451479758 3.50 f=rho2
END
FDE
PW91K
END
SUBEXCI
CTHRES 10000.00
SFTHRES 0.00010000
COUPLBLOCK
END
END INPUT
eor