Multiwfn forum

quoske

Member

Registered: 2019-06-22

Posts: 3

Transition dipole moment of organic molecules

Hi,

I'm a postgraduate student who is totally new to quantum chemistry calculation, and currently having trouble calculating transition moment of certain molecules.

I used Gaussian09/GaussView16 to calculate data shown below:
1. Geometry optimization of the ground state molecule using DFT.
2. Excited state of the optimized molecule using TDDFT by job type of "Energy"

Then I converted the result of data2 to ".fch" and tried to run a calculation in Multiwfn.

The commands I tried were:
18 // Electron excitation analysis
5 // Calculate transition electric dipole moments between...

However, after command 5 the program tells me to input path of Gaussian output file and I don't know what to do.
Does this mean that data2 calculated by Gaussian is invalid for the dipole moment calculation?

I apologize in advance if this question was too basic to ask on this forum.

Best regards

sobereva

Tian Lu (Multiwfn developer)

From: Beijing

Registered: 2017-09-11

Posts: 1,768

Website

Re: Transition dipole moment of organic molecules

Hi,

Please never use GaussView 16 to create keywords and submit task. I strongly always manually write proper keywords and manually submit task to Gaussian, in this case you can flexibly employ any keyword that you really need and the path of output file will be very clear.

There are many example Gaussian input files for performing electron excitation analysis in Multiwfn, for example, the "examples\excit\D-pi-A.gjf", please take this file as example.

Please also do not forget to carefully follow relevant examples in Section 4.18 of Multiwfn manual.

Best regards,

Tian

quoske

Member

Registered: 2019-06-22

Posts: 3

Re: Transition dipole moment of organic molecules

Thank you very much for quick response!!

I followed the example from manual section 4 and manually input the keywords in gaussian to calculate TDDFT.

In Multiwfn, I am able to input .fch file to proceed. However, I have trouble entering the output files: it shows the error messege that it "Cannnot find this file, please input again",
even though the output file is in the same folder as .fch file.

Do you have any idea why this is happening?

I tried the example files of "D-ppi-A", and they work without any problem.

Best regards

sobereva

Tian Lu (Multiwfn developer)

From: Beijing

Registered: 2017-09-11

Posts: 1,768

Website

Re: Transition dipole moment of organic molecules

If you are using Windows version, please directly drag the icon of the file into Multiwfn window, the correct path will be automatically generated, and thus you don't need to manually input the path and can completely avoid inputting wrong path/filename.

If you are using Linux version and you are quite confused about the file path, please input absolute path rather than relatively path. (you can also input relative path, but please make clear what is "current directory", see Page 2 of Multiwfn manual)

quoske

Member

Registered: 2019-06-22

Posts: 3

Re: Transition dipole moment of organic molecules

It seems that I had saved my output files into wrong folder.
I am now able to calculate dipole moment.

Thank you very much for the kindness!!
I really appreciate the program.