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Re^2: How to check for acceptance of Kasha's rule from TDDFT data...?

Pavlo Solntsev

Kasha's rule doesn't always work. For example, if you have redox active group near chromophore.

Try to figure out absorbtion--emission situation for a porphyrin.


On Wed Sep 24 '14 9:11pm, Siddheshwar Chopra wrote
>Dear users,
>Somebody please help me in understanding this concept. I need to know that by setting istate =1 in emission spectra calculation, I am actually setting or calculating the de-excitation from the S1 state. Am I correct? If yes, then the TDDFT o/p gives me a set of transitions possible for every excited state (set by variable nstate).What are these nstates now? Do they hold any significance in S1-->S0 transition? Do we mean that these are the vibrational levels of S0 level? Please explain this in the light of kasha's rule.
>I am worried because I am unable to point out the emission wavelength. Please help me Alex Sir and Pavlo Sir. Please help me in analysing the emission calculations.

>Kind Regards,
>n Tue Sep 23 '14 12:21pm, Siddheshwar Chopra wrote
>>Dear Users,
>>Please have a look at the attached file which contains a table describing the contributions/transitions from first four states only for both the absorption and emission calculations. For absorption, I understand that the final state can be any of the excited states which has highest osc. strength. Am I right? But my doubt is regarding kasha's rule... If you see the emission data, the first excited state has a very low oscillator strength of 0.004 (HOMO-->LUMO(97 at 2678.9 nm. However the higher states have a better contribution than this state. So please tell me how to analyse this properly. To my knowledge emission wavelength is around 600-730nm.
>>I would be grateful for any help.

>>Kind Regards,

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