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Re^9: Help needed with the Transition density matrix determination and analysis....

Alex Granovsky
gran@classic.chem.msu.su


Hi,

no, transition dipole moment matrix does not serve your purposes.

Kind regards,
Alex Granovsky


On Mon Sep 29 '14 11:49am, Siddheshwar Chopra wrote
---------------------------------------------------
>Dear Alex,
>Sorry for asking you again. There is a relation between transition density and transition dipole. So please pardon me if I ask:: Will extracting Transition dipole moment matrix serve the purpose of pointing out "spatial location of the transition from ground to excited state"? It is a NSTATE*NSTATE matrix as you told too.

>Kind Regards,





>
>
>On Mon Sep 29 '14 11:13am, Siddheshwar Chopra wrote
>---------------------------------------------------
>>Dear Alex,
>>Thank you for the detailed explanation. I really need a TDDFT PUNCH file now to understand what you have suggested. I will get back once I extract this matrix.
>>In the meanwhile has anyone got a program for this extraction? It would be a great help.

>>Kind Regards,

>>On Sun Sep 28 '14 0:20am, Alex Granovsky wrote
>>----------------------------------------------
>>>Dear Siddheshwar,

>>>I'm sorry for delay with my answers.

>>>As to your questions:

>>>>>I would be really grateful if you could throw some light on the transition density matrix calculation. Is it possible to determine the matrix from TDDFT output file? IF yes then I would attach one file. Kindy let me know Sir.

>>>No, it is impossible to compute 1-P TDM (one-particle transition
>>>density matrix) based only on the information found in the output
>>>file.

>>>>>>Dear Pavlo Sir and Alex Sir,
>>>>>>Thank you so much for the useful information. Alex sir I am really happy to know that it is possible to find TDM from PUNCH file (from TDDFT calc.). I would request you to elaborate the process for the same. Right now I dont have any punch file with me. Can you explain with the help of any punch file? Once that is clear, I will look for the program.

>>>The required information that can be extracted from the PUNCH file
>>>is the content of the $VEC group and $TDVEC group. Each $VEC group
>>>contains current molecular orbitals. The $TDVEC group contains X
>>>and Y components of the TDDFT eigenvectors. For hybrid DFT, X
>>>component is written first, then Y component follows. These records
>>>are repeated for each root of TDDFT i.e. there are 2*NSTATE records
>>>in total. As to individual record, it contains NVIR*NOC elements,
>>>where NVIR is the number of virtual orbitals and NOC is the number
>>>of active occupied orbitals i.e. the number of occupied orbitals
>>>minus number of frozen core MOs. These numbers form matrices X
>>>and Y, with virtual orbital index running first, then occupied
>>>orbital index.

>>>Once you extracted X and Y matrices, the transition density matrix
>>>in MO basis is simply sum of X and Y blocks: Tmo = X+Y. If you need,
>>>you can convert it into MO basis set using the following equation:

>>>

  Tao = S*V * Tmo * (S*V)-dagger 

>>>where V are the matrix of MO coefficients and S is the matrix of
>>>overlap integrals. The latter can be printed out by running
>>>Firefly with exetyp=INT1

>>>>>>Also, Sir I found that transition dipole moment matrix in the TDDFT o/p file is of the size NSTATE X NSTATE. Can you explain how to analyse this? I find the x,y,z data corresponding to an i,j element.

>>>This is a matrix of transition dipoles between states Si and Sj.
>>>This information can be used, for instance, to compute
>>>two-photon absorbance (TPA)cross-sections using sum over states
>>>approach (SoS)

>>>> Does the magnitude of this dipole moment = sqrt(x^2+y^2+z^2)?

>>>Yes it is (note in the printout atomic units are used throughout).

>>>Kind regards,
>>>Alex Granovsky


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