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sobereva

Tian Lu (Multiwfn developer)

From: Athens, Greece

Registered: 2017-09-11

Posts: 2,301

Website

Determination of pure CT state of D-A complex

Recently a Multiwfn user asked a question

How to identify the pure charge transfer (CT) states between donor-acceptor molecule by NTO analysis?

It is reported by M. -Y Li et al. (attached herewith) that the NTO analysis has been performed to examine the electronic excitation characteristics comprehensively to gain the pure CT states.

I think my reply is also useful for some other Multiwfn users, therefore I paste my reply here

If after forming NTO analysis for an excited state, you find there is a single NTO-pair having contribution almost 100% (or at least higher than 85%), and the two NTOs almost purely locate on the donor part and acceptor part, respectively, then you can say this is a pure CT state.

In my opinion, a much better way is performing IFCT analysis, see Section 3.21.8 of Multiwfn manual for theory introduction and 4.18.8 for example. You can find two fragment, one corresponds to donor part and another one corresponds to acceptor part. Assume the amount of net charge transfer from donor to acceptor is higher than e.g. 0.85, you can the percentage of CT character of 85%, or you can even identify this is a pure CT state.

Arivu

Member

Registered: 2025-12-27

Posts: 15

Re: Determination of pure CT state of D-A complex

Dear Prof. Tian,
     I have used my ORCA output as molden input and have done the IFCT analysis, defining 3 fragments (Strong donor + pi bridging part + weak donor). Now the total intrinsic CT+LE is only 76.476 %. But in the manual, it says total will be 100 %. Where the remaining gone? If I have done both donor + bridge as acceptor results, I have also attached.

Last edited by Arivu (2026-10-04 18:33:48)

sobereva

Tian Lu (Multiwfn developer)

From: Athens, Greece

Registered: 2017-09-11

Posts: 2,301

Website

Re: Determination of pure CT state of D-A complex

Hello,

I don't know what "used my ORCA output as molden input" means. For ORCA users, both molden input file and ORCA output file are needed.
I also cannot answer your question without your ORCA input file. Please make sure that you have properly set "tprint" as mentioned in Section 3.21.A.3 of Multiwfn manual, otherwise many nonnegligible configurations will be ignored and this issue may thus happens.
From your screenshot, I can only find you defined two rather than three fragments. Some atoms, such as atom 10, is missing. This results in the sum of the contributions from all fragments not equaling 100%.

Arivu

Member

Registered: 2025-12-27

Posts: 15

Re: Determination of pure CT state of D-A complex

Dear Prof. Tian,
    Thank you so much for your reply. The error was due to atom 10 being missing, that exactly you pointed out. Now I am getting the correct results after properly updating the fragment selection.
I mean .gbw file imported into Multiwfn (inside settings.ini, I have given the orca_2mkl path to convert to molden input file) and did the calculation, during the calculation Multiwfn took .out file of ORCA as well.
The results are attached after updating the fragment numbers.
Once again thank you

Last edited by Arivu (2026-10-05 07:26:47)