Multiwfn forum / Charge Transfer for S1->T1 conversion

Re: Charge Transfer for S1->T1 conversion

dummy@example.com (sobereva) — Wed, 09 Apr 2025 13:00:38 +0000

Transition density is very different to charge density difference, there is no direct relationship among them. Please check Section 3.21.1 of Multiwfn manual to understand definition of transition density.

Re: Charge Transfer for S1->T1 conversion

dummy@example.com (andrzejek) — Tue, 08 Apr 2025 06:34:02 +0000

Thank you cordially! You mention CDD, so you refer to option:
"15 Output cube file of CHARGE DENSITY DIFFERENCE to current folder"
What would happen if I use "13 Output cube file of TRANSITION DENSITY to current folder"?
Best

Re: Charge Transfer for S1->T1 conversion

dummy@example.com (sobereva) — Tue, 08 Apr 2025 00:34:30 +0000

To calculate electron density difference between S1 and T1 via Multiwfn, you should do:
(1) Using hole-electron analysis module (subfunction 1 of main function 18) to calculate electron density difference between S1 and S0, then export the grid data as CDD.cub and manually rename it as S1CDD.cub. See Section 4.18.1 of Multiwfn manual for example.
(2) Similarly, generate electron density difference between T1 and S0, and store as T1CDD.cub.
(3) Using Multiwfn to generate difference grid data between S1CDD.cub and T1CDD.cub (see the grid data mathematical operations exemplified in Section 4.13.2 of Multiwfn manual), then the grid data in memory will corresponds to electron density difference between S1 and T1. Then you can directly visualize it as isosurface map in Multiwfn.

As I mentioned in past posts, you may also perform NTO analysis for T1 and S1 respectively, if their hole-NTO happen to be similar, then you can simply visually compare electron-NTO of T1 and that of S1 to study electron transition in terms of orbital wavefunctions.

Re: Charge Transfer for S1->T1 conversion

dummy@example.com (andrzejek) — Mon, 07 Apr 2025 20:00:57 +0000

Hi, I’m using ORCA 6.0 to run calculations with B3LYP/def2-TZVP in SMD solvent (water), using the TDA approximation.
The point is, the SOC values are quite high for the S? → T? transition, but there’s no apparent change in orbital shape (angular momentum like in El Sayed rule). So I suspect this elevated SOC might be related to charge transfer, since the system is an anion?
Actually, I’m wondering whether I should analyze the charge density difference between these two states, or if it would be enough to just look at what’s happening in T? (if the charge transfer happens there by means of hole-electron analysis)?
Thanks.

Re: Charge Transfer for S1->T1 conversion

dummy@example.com (sobereva) — Mon, 07 Apr 2025 00:02:15 +0000

Please describe which quantum chemistry program and computational level you are using.

Charge Transfer for S1->T1 conversion

dummy@example.com (andrzejek) — Sun, 06 Apr 2025 20:34:18 +0000

Hello,
Could someone please provide a detailed, step-by-step explanation on how to visualize charge transfer—specifically, the electron density difference between the S? and T? states, indicating regions of depletion and accumulation during the process?
Thank you!