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Re^3: wrong oscillator strengths for high symmetry molecules in TDDFT calculation

Alex Granovsky


you should distinguish program errors (there are none at present
in the Firefly's DFT/TDDFT code) and errors due to use of simplified
and inaccurate model (like TDDFT is).

>>2. As to second part of your question, could you please be a bit
>>more specific. It is hard to answer without looking into actual
>>output files. Note, in C2 group, there are no forbidden transitions
>>at all. Does your question mean that you got large transition
>>moments for forbidden transitions in Ci group?

>I did not get large transition moments for forbidden transitions in Ci group.

Small non-zero transition moments for forbidden transitions are
usually due to numerical noise/use of finite grid used in DFT/TDDFT
calculations. Use larger grid or explicit symmetry in TDDFT.

Kind regards,
Alex Granovsky

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