Electronic coupling - CDFT-CI

Questions
#1

Dear users and developers!
I am trying to calculate electronic coupling for (Guanine/Thymine) GT-stacked Base pair, by using CDFT-CI method.
The input goes as follows,
$comment
Use CDFT-CI method to calculate the electronic coupling for electron-transport
$end

$cdft
1.0
1.0 17 31
1.0
1.0 17 31 s

1.0
1.0 1 16
1.0
1.0 1 16 s
$end

$rem
exchange wB97X-D
basis cc-pVTZ
geom_opt_maxcyc 500
max_scf_cycles 5000
mem_static 8000
mem_total 70000
symmetry off
sym_ignore true
unrestricted true
cdftci true
cdftci_print 1
CDFT_BECKE_POP TRUE
thresh 14
solvent_method pcm
$end

$pcm
theory cpcm
method swig
solver inversion
HeavyPoints 194
HPoints 194
radii bondi
vdwscale 1.2
$end

$solvent
Dielectric 78.4
$end

$molecule
-1 2
N 4.8702930691804953 1.6511622689767904 0.4368633485145778
C 5.4345039223649270 1.8293323750326802 -0.8014425481820455
N 4.5450001856120954 1.8907472061059274 -1.7606452453739938
C 3.3345728337408964 1.7342309951783972 -1.1129483232772084
C 2.0044843283470599 1.6910265655849706 -1.6277290823999802
O 1.6191381818810808 1.8041843832181448 -2.7936721113148724
N 1.0731670686569401 1.4766030884545520 -0.5983943829403969
C 1.3631901413967322 1.3337927341728240 0.7360183925592679
N 0.3277463348551760 1.0617311612035503 1.5653175622998492
N 2.5883782342344870 1.3955047281868909 1.2167532404394819
C 3.5213197600340598 1.5840928209403435 0.2563794767081115
H 5.3635991644843566 1.5690412583267563 1.3165550518455251
H 6.5062590255770312 1.9088986353018735 -0.9226581205345651
H 0.1077632847152288 1.4038173956822173 -0.9037713347532285
H 0.5172549309378732 1.1386112773348178 2.5556289526880440
H -0.6161797706186397 1.2878187685919555 1.2816161003805040
N 4.4461695710447762 -1.7219111834313465 0.9103137259230094
C 3.1664792136482478 -1.7979121414863000 1.3903458527571364
O 2.8926422473602109 -1.8654891456038420 2.5847665993397126
N 2.2054032141703344 -1.8021261437107461 0.4029360779978748
C 2.4116469562574592 -1.7334933514930504 -0.9719131949998027
O 1.4466364921271873 -1.7549012742984469 -1.7357921901198434
C 3.8032902604936454 -1.6364480438478184 -1.3904993997097597
C 4.1134258847865635 -1.5155560856536463 -2.8516980419001889
C 4.7508822159956559 -1.6401467437307682 -0.4272464511256829
H 3.6782116967881109 -0.5982336862764428 -3.2637826029099815
H 3.7025666487808637 -2.3624865251406759 -3.4117335135437488
H 5.1950655169650268 -1.4825593731696591 -3.0088620467216205
H 5.8104997081508980 -1.5750301838996963 -0.6495319566787436
H 1.2435893268125604 -1.8557292768165761 0.7232426563965806
H 5.1899397998582870 -1.7125948632264194 1.5971336539521819
$end

I have a questions from output,
As I understand CDFT Becke population should be equal to constrained charge (in my calculations charge constrained = 1 that is equal to charge constrained for electron transport)
But the total Becke population number I got from output ( -0.0188) is not approximate to 1.
I tried with another water dimer molecules with the same input as above, I got total Becke population equal to charge constrained value 1.

Can anyone make me clear about the Toal Becke population should be equal to charge constrained or not? Is there any other ways to explain this?

Thank you for your help,
Roshan

#2

This has been address previously, see here:

#3

As John mentioned, you can refer to the previous thread. You can also see the description after Example 5.32 (5.11.4 Examples‣ 5.11 Methods Based on “Constrained” DFT ‣ Chapter 5 Density Functional Theory ‣ Q-Chem 6.1 User’s Manual). Could you also share the snippt of output where you got -0.0188? I used the provided input section and I got total excess electron of 0.996008, which is close to 1.

#4

Thank you so much for your answer. Now, I got 0.99 close to 1.

#5

Thank you so much that helps me a lot.