I have a question regarding how to correctly define the CDFT constraint for my donor–acceptor system. My system consists of an OPP–TEA complex with a total of 54 atoms:
- Atoms 1–32 correspond to the OPP fragment (acceptor)
- Atoms 33–54 correspond to the TEA fragment (donor)
I am trying to model single-electron transfer from TEA to OPP (TEA → OPP), corresponding to OPP⁻ and TEA⁺.
In my current input, I used the following CDFT block:
$molecule
0 1
H -3.15586000 -2.07760000 -0.59452000
C -3.66695000 -1.16159000 -0.31493000
C -2.90802000 0.00000000 0.00000000
C -3.66695000 1.16159000 0.31493000
H -3.15586000 2.07760000 0.59452000
C -5.05390000 1.15739000 0.31223000
H -5.58500000 2.07098000 0.56890000
C -5.77352000 0.00000000 0.00000000
H -6.85892000 0.00000000 0.00000000
C -5.05390000 -1.15739000 -0.31223000
H -5.58500000 -2.07098000 -0.56890000
C -1.45994000 0.00000000 0.00000000
C -0.68631000 1.20442000 0.00521000
C 0.68631000 1.20442000 -0.00521000
C 1.45994000 -0.00000000 0.00000000
C 0.68631000 -1.20442000 0.00521000
C -0.68631000 -1.20442000 -0.00521000
C 2.90802000 -0.00000000 0.00000000
C 3.66695000 1.16159000 -0.31493000
C 5.05390000 1.15739000 -0.31223000
C 5.77352000 -0.00000000 0.00000000
C 5.05390000 -1.15739000 0.31223000
C 3.66695000 -1.16159000 0.31493000
H -1.19209000 2.16631000 -0.00708000
H 1.19209000 2.16631000 0.00708000
H 1.19209000 -2.16631000 -0.00708000
H -1.19209000 -2.16631000 0.00708000
H 3.15586000 2.07760000 -0.59452000
H 5.58500000 2.07098000 -0.56890000
H 6.85892000 -0.00000000 0.00000000
H 5.58500000 -2.07098000 0.56890000
H 3.15586000 -2.07760000 0.59452000
N 0.00039100 0.00467400 2.90192500
C 1.37462100 0.46378100 2.91384600
C 1.73135700 1.14866000 4.23998800
C -0.28865800 -1.41522700 2.91167600
C 0.14265000 -2.07049000 4.23080600
C -1.08432100 0.96539700 2.92133400
C -1.87588000 0.90399600 4.23432200
H 1.47514700 1.17701700 2.08789800
H 2.02119500 -0.39382500 2.72656200
H 1.10511000 2.02556700 4.41753600
H 2.77091000 1.47525000 4.17632900
H 1.62721100 0.45566700 5.07677800
H 0.26954600 -1.85493600 2.07734200
H -1.35631400 -1.54746800 2.73539600
H 1.21979500 -1.98432800 4.38704700
H -0.11647800 -3.12942700 4.17649800
H -0.38077200 -1.62152700 5.07709700
H -1.73900400 0.71339400 2.07891300
H -0.66270600 1.95782100 2.76177900
H -2.33516200 -0.07589500 4.37965500
H -2.66857300 1.65238400 4.17975800
H -1.23259100 1.13162800 5.08662500
$end
$rem
JOB_TYPE Optimization
METHOD wB97X-D
BASIS 6-31G**
SCF_CONVERGENCE 8
SCF_MAX_CYCLES 800
SCF_ALGORITHM DIIS_GDM
GEOM_OPT_MAX_CYCLES 200
UNRESTRICTED TRUE
SYMMETRY FALSE
SYM_IGNORE TRUE
CDFT TRUE
CDFT_PRINT TRUE
CDFT_BECKE_POP TRUE
CDFT_THRESH 8
BECKE_SHIFT UNSHIFTED
XC_GRID 000099000590
SOLVENT_METHOD PCM
$end
$pcm
THEORY CPCM
heavypoints 590
method swig
radii bondi
solver inversion
$end
$solvent
DIELECTRIC 37.5
OPTICALDIELECTRIC 1.8068
$end
$cdft
2
1 1 32
$end
@@@
$molecule
read
$end
$rem
JOB_TYPE Freq
METHOD wB97X-D
BASIS 6-31G**
SCF_CONVERGENCE 8
VIBMAN_PRINT 4
UNRESTRICTED TRUE
SYMMETRY FALSE
SCF_ALGORITHM DIIS_GDM
SYM_IGNORE TRUE
SOLVENT_METHOD PCM
CDFT TRUE
CDFT_PRINT TRUE
CDFT_BECKE_POP TRUE
CDFT_THRESH 8
BECKE_SHIFT UNSHIFTED
XC_GRID 000099000590
MEM_TOTAL 248000
MEM_STATIC 4000
$end
$pcm
THEORY CPCM
heavypoints 590
method swig
radii bondi
solver inversion
$end
$solvent
DIELECTRIC 37.5
OPTICALDIELECTRIC 1.8068
$end
$cdft
2
1 1 32
$end
After convergence, this enforced +2 excess electrons on the first fragment (OPP). This seems to result in a two-electron transfer state rather than the intended single-electron transfer.
But when I tried with the following CDFT block I am getting convergence issue.
$cdft
1
1 1 32
$end
Could anyone please guide me how to correctly set up CDFT block?