Hello, I am trying to perform a CDFT-CI calculation in Q-Chem 6.4 for an intramolecular donor–bridge-acceptor system that is an anion radical (overall charge = −1, multiplicity = 2). My goal is to model electron transfer between two fragments:
- Donor region: atoms 1–21
- Acceptor region: atoms 38–54
I am having difficulty determining the correct CDFT-CI constraints. My current input file:
$molecule
-1 2
C -1.05752 -1.39603 0.86890
C -1.98340 -1.07935 1.87509
C -3.34662 -1.24635 1.73247
C -3.93541 -1.76228 0.52891
C -2.97880 -2.08119 -0.49354
C -1.62407 -1.89930 -0.31619
C -5.34379 -1.95340 0.36716
C -6.31069 -1.47018 1.31826
C -7.66613 -1.66360 1.15836
C -8.19340 -2.35200 0.05048
C -7.27318 -2.83557 -0.89836
C -5.91515 -2.64747 -0.75702
H -1.58975 -0.70472 2.81804
H -3.98378 -1.00946 2.57968
H -3.32679 -2.46107 -1.44983
H -0.94209 -2.15306 -1.12869
H -5.97198 -0.90580 2.18253
H -8.34434 -1.26407 1.91282
H -9.26240 -2.50178 -0.06982
H -7.63806 -3.37920 -1.77023
H -5.25798 -3.06873 -1.51271
C 2.32798 0.56276 0.74525
C 3.14409 -0.64894 1.22539
C 2.49538 -1.29493 2.46371
C 0.95405 -1.19003 2.45442
C 0.44023 -1.18585 1.00607
C 0.89635 0.13018 0.31945
H 2.23755 1.24048 1.60426
H 4.17184 -0.34247 1.44840
H 3.21508 -1.37812 0.40891
H 2.79317 -2.34859 2.51161
H 2.88750 -0.82228 3.37161
H 0.64954 -0.26026 2.95605
H 0.52972 -2.01873 3.03046
H 0.95180 -2.01863 0.48928
H 0.84777 0.00310 -0.76789
H 0.20224 0.94114 0.56352
C 5.43790 5.25355 -1.94193
C 5.64548 4.63013 -3.19452
C 5.16854 3.36453 -3.42033
C 4.46393 2.66271 -2.40928
C 4.25120 3.28906 -1.15122
C 4.75746 4.59930 -0.94725
C 3.95839 1.35053 -2.60502
C 3.28103 0.70388 -1.60857
C 3.05532 1.31836 -0.34497
C 3.54208 2.58620 -0.14148
H 5.81806 6.25633 -1.77219
H 6.18181 5.15878 -3.97642
H 5.32100 2.88069 -4.38152
H 4.59600 5.07771 0.01512
H 4.11384 0.86582 -3.56523
H 2.90138 -0.29899 -1.78267
H 3.38478 3.07583 0.81721
$end
$rem
BASIS = 6-31G**
METHOD = wB97X-D
CDFTCI = 1
CDFTCI_PRINT = 2
GUI = 2
JOB_TYPE = SP
SCF_MAX_CYCLES = 200
SYMMETRY = FALSE
SYM_IGNORE = TRUE
UNRESTRICTED = TRUE
MEM_TOTAL = 248000
MEM_STATIC = 4000
$end
$cdft
1.0
1.0 1 21
1.0
1.0 1 21 s
---
1
1.0 38 54
1
1.0 38 54 s
$end
I am getting an “invalid charge and spin” error in the output file, so I am not sure whether my CDFT-CI constraints are defined correctly. Since this is a covalently linked donor–bridge–acceptor system, should I include the bridge atoms in the CDFT-CI regions, or is it sufficient to define only the donor (atoms 1–21) and acceptor (atoms 38–54) fragments?
Any guidance would be greatly appreciated.