On the calculation of charge transfer between donor and acceptor

sobereva · 2019-11-04 23:59:07

Recently one of my collaborators asked me a question about which way is the most suitable way of calculating charge transfer between donor and acceptor in weak interaction complex, I share my view point below because it may be useful for some Multiwfn users.

There are two known popular ways to calculate charge transfer based on orbital interaction, the first one is the NBO, the charge transfer is evaluated based on off-diagonal terms of Fock matrix (which reflects coupling strength between NBO pairs) and diagonal terms of Fock matrix (corresponding to NBO energies); the second way is charge decomposition analysis (CDA), which is supported by Multiwfn, see Section 4.16 of Multiwfn manual for example. CDA is employed very commonly for studying charge transfer between transition metal and ligands. The difference in these two ways is that the former is analyzed based on NBO orbitals, while the latter is usually based on molecular orbitals calculated for respective fragments.
Evaluation of charge transfer (delta_q) in terms of these orbital interaction models is able to get deeper insight into the nature and source of charge transfer phenomenon, however, the net amount of delta_q obtained in these ways are never as accurate as the delta_q calculated by summing up atomic charges as fragment charge (and then compare it with the net charge of the fragment at isolated state), because orbital interaction models ignore possible high-order interactions, polarization and coupling between different interacting orbital pairs.
So, both kinds of ways of evaluating delta_q may be used in practical study, they have their own advantages.

saeed_E · 2019-12-29 07:30:28

Dear Professor Lu,
Too many thanks for your kindness to share your highly important, valuable, and informative explanations.

Sincerely yours,
Saeed

prasanta13 · 2020-01-09 13:57:50

Prof Lu,
I am trying to model the electron transfer from superoxide radical to benzoquinone molecule in the ground state. Can it be done with CDA approach? Or there are other better approaches?

sobereva · 2020-01-09 15:49:12

prasanta13 wrote:

Prof Lu,
I am trying to model the electron transfer from superoxide radical to benzoquinone molecule in the ground state. Can it be done with CDA approach? Or there are other better approaches?

If you are only interested in amount of total charge transfer between the superoxide radical and benzoquinone, you do not need to use CDA. You can simply calculate fragment charge of the superoxide radical fragment (namely sum of atomic charges in the fragment), it directly corresponds to amound of net charge transfer.

Note that Multiwfn is able to directly print fragment charge, see this video illustration:
Using Multiwfn to calculate fragment charge of a molecule
https://youtu.be/xKvOLFbeGoc

xdongmo · 2020-02-21 18:00:50

Hi! I am new in the forum whish to find out how to post here. Ask a question etc. Thanks

sobereva · 2020-02-21 19:21:15

xdongmo wrote:

Hi! I am new in the forum whish to find out how to post here. Ask a question etc. Thanks

Please feel free to post in this forum. There is no restriction.

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#1 2019-11-04 23:59:07

On the calculation of charge transfer between donor and acceptor

#2 2019-12-29 07:30:28

Re: On the calculation of charge transfer between donor and acceptor

#3 2020-01-09 13:57:50

Re: On the calculation of charge transfer between donor and acceptor

#4 2020-01-09 15:49:12

Re: On the calculation of charge transfer between donor and acceptor

#5 2020-02-21 18:00:50

Re: On the calculation of charge transfer between donor and acceptor

#6 2020-02-21 19:21:15

Re: On the calculation of charge transfer between donor and acceptor

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