Firefly and PC GAMESS-related discussion club

Learn how to ask questions correctly  
We are NATO-free zone

Re^5: Can't figure out how to find emission spectra of Benzene...

Siddheshwar Chopra

Dear Pavlo,
Sorry for replying late. I just went through all the files you had provided. I am really grateful to you for taking out time to make us understand this so well. I am really thankful to you.
Pavlo I checked all the files and would be glad if you could answer some basic questions:

1) The emission spectra is obtained from the file "pp_opt_s1_tddft.out"?
2) From S1*--> S1... How to use and understand state tracking? I actually don't understand what I am supposed to do with it. I just know how to turn it on. What happens if I switch it off?
3) You said "1st excited state is B3U"...and used the same optimized coordinates of S0 while optimizing the S1*. Is it right? What should I do with the "1st excited state is B3U"? This step is very important for understanding. By using the optimized coords. of S0 in optimizing S1*, do you mean that the coordinates of atoms don't change in excited state?
4) You have used PCM calculations all throughout.. They don't seem time consuming. What all solvents I could use for the same? Do I have acetonitrile available?

Pavlo until your help, I was in this notion that I should get the most probable orbitals from UV-Vis. calculations and then optimize them for S1 and then obtain the emission spectra. But you haven't talked about most probable orbitals anywhere... Where do I apply the concept I just mentioned then?

Kind Regards,

On Thu Jun 12 '14 10:18am, Siddheshwar Chopra wrote
>Dear Pavel,
>Your suggestions have always been valuable to me. I will start working on your files and will let you know in case I need your help.

>Kind Regards,

>On Wed Jun 11 '14 4:17pm, Pavlo Solntsev wrote
>>I attached example how to do Luminescence calculation for porphyrin molecule. For more detailed information please, check manual AND this forum.

>>Salvation model has not been programmed for TDDFT+gradient. Therefore, optimization of the excited state was done without solvent correction. However, this correction was included into spectra calculation.

>>Very often geometry optimization of the excited state brakes a true molecular symmetry. Keep this in mind.

>>For more complex systems state of interest may be different, not S1. It is especially true if you have a donor group in your molecule and thus HOMO....HOMO-x belong to the donor, but you are looking for emission within porphyrin core. In such case you need identify the state of interest based on TDDFT(ground state) and knowledge.

>>Good luck.

>>On Tue Jun 10 '14 10:16pm, Siddheshwar Chopra wrote
>>>Dear Alex,
>>>I searched a lot on this forum regarding the same. What you told is right and I know these too. But I want to step by step how to optimize  the S1? say for  benzene.
>>>And then how should I determine S0--> S1 (optimized)?
>>>Please help me stepwise. Any i/p files would be of great help.. I have noted from TDDFT calc of benzene that orbitals 17-24 are most dominant ones. How do I proceed next?

>>>Kind Regards,

>>>n Tue Jun 10 '14 7:43pm, Alex Granovsky wrote

>>>>for emission spectra you need to optimize S1 geometry and then compute
>>>>vertical transition from S0 to S1 at optimized geometry of S1.

>>>>Kind regards,
>>>>Alex Granovsky
>>>>On Sat Jun 7 '14 9:10pm, Siddheshwar Chopra wrote
>>>>>Dear Firefly users,
>>>>>I need some real help in determining the emission spectra (S1--->SO*) of benzene.
>>>>>I have understood till optimizing the ground state and then obtaining the vertical transition from SO--->S1*...
>>>>>Please help me now what I should do next? Any i/p files would be welcomed.

>>>>>Kind Regards,

[ Previous ] [ Next ] [ Index ]           Mon Jun 16 '14 11:00am
[ Reply ] [ Edit ] [ Delete ]           This message read 595 times