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cy21d042

Member

Registered: 2022-11-21

Posts: 6

Transition Dipole moment of Excited state

How do we know the transition dipole moment of a particular excited state? Also, why are there differences between the dipole moment values obtained from Gaussian TD-DFT calculations and Multiwfn?

sobereva

Tian Lu (Multiwfn developer)

From: Beijing

Registered: 2017-09-11

Posts: 1,468

Website

Re: Transition Dipole moment of Excited state

Transition dipole moments between ground state and excited states can be direct obtained from Gaussian output file. If what you need is dipole moment of an excited state, you can follow example in Section 4.18.5 of Multiwfn manual.

Note that in order to use Multiwfn to calculate transition dipole moments between ground state and excited states, or dipole moments of excited states, IOp(9/40=4) should be used in Gaussian TDDFT input file, otherwise the result of Multiwfn will be inaccurate, this point has been clearly mentioned in Section 3.21.A.

cy21d042

Member

Registered: 2022-11-21

Posts: 6

Re: Transition Dipole moment of Excited state

Thankyou for letting me know.

cy21d042

Member

Registered: 2022-11-21

Posts: 6

Re: Transition Dipole moment of Excited state

I tried the gaussian TDDFT calculation using the keyword IOp(9/40=4). Still, there is a difference in the print values obtained for the transition dipole moment of any excited state from gaussian and multiwfn. I am also attaching the screenshot of the values obtained for a particular excited state from gaussian and multiwfn.

Thanks in advance.

sobereva

Tian Lu (Multiwfn developer)

From: Beijing

Registered: 2017-09-11

Posts: 1,468

Website

Re: Transition Dipole moment of Excited state

Please send me your Gaussian input and output files as well as fch file via E-mail, and show me all commands you inputted in Multiwfn, so that I can exactly understand the problem you encounted.

sobereva

Tian Lu (Multiwfn developer)

From: Beijing

Registered: 2017-09-11

Posts: 1,468

Website

Re: Transition Dipole moment of Excited state

I have received your files. I cannot reproduce data in your screenshot of Multiwfn window.
I am using latest version of Multiwfn, after booting up Multiwfn, load SN5_PC61TD.fchk, then input
18
5
SN5_PC61TD.out
1

Then I obtain following data

 Transition electric dipole moment between ground state (0) and excited states (
a.u.)
     i     j         X             Y             Z        Diff.(eV)   Oscil.str
     0     1    -0.0184478     0.0876744    -0.0753031     2.41780     0.00081
     0     2     0.0064682     0.0153879    -0.0174119     2.44450     0.00003
     0     3     0.0198596     0.0315486    -0.0073035     2.52350     0.00009
     0     4    -0.0021030     0.0157768     0.0032594     2.55180     0.00002
     0     5     0.9767020     5.4012090    -0.2903876     2.64460     1.95744
     0     6     0.0054606     0.0264971     0.0191388     2.66090     0.00007
     0     7    -0.1082712    -0.0673842     0.0021334     2.70910     0.00108
     0     8     0.0057811    -0.0038004    -0.0019630     2.77590     0.00000
     0     9     0.0376454     0.2034906    -0.0080345     2.82680     0.00297
     0    10     0.0052998    -0.0318288    -0.1068360     2.86030     0.00087
     0    11    -0.0478869    -0.0446300    -0.0779666     2.94400     0.00075
     0    12     0.0948701    -0.0508343    -0.1396014     2.95570     0.00225
     0    13     0.0037044     0.0017789     0.0021912     2.98590     0.00000
     0    14     0.0334592     0.0437068    -0.0193586     3.07180     0.00026
     0    15    -0.0542795     0.0433833     0.0345362     3.10290     0.00046
     0    16    -0.0470189     0.1178708     0.0920791     3.12110     0.00188
     0    17    -0.0044826    -0.0839705     0.0176850     3.13810     0.00057
     0    18    -0.0185949    -0.4634157     0.1564067     3.17530     0.01864
     0    19    -0.1436093     0.0093767    -0.0339999     3.23550     0.00173
     0    20    -0.2572736     0.0309617    -0.6497620     3.34660     0.04012

As you can see, the 0-14 result 0.0334592     0.0437068    -0.0193586  doesn't differ from that printed by Gaussian (0.0332      0.0361     -0.0098) too much by absolute magnitude. The quantitative discrepancy mainly comes from that only configuration coefficients larger than 1E-4 are taken into account. If IOp(9/40=5) is used, I find the result will be 0.0345300     0.0367532    -0.0109116, which is notably more close to the Gaussian result and the difference can be fully ignored.

cy21d042

Member

Registered: 2022-11-21

Posts: 6

Re: Transition Dipole moment of Excited state

Thank you very much for your response.