[DFTB-Plus-User] Negative frequencies in excited state optimization..

[siddheshwar chopra]

Dear All,
I am trying to optimize the lowest excited state of a material. I am
getting the following frequencies:

Starting main program

 Vibrational modes (cm-1):
    1  -31.47
    2  -10.99
    3   -4.25
    4   -0.17
    5    0.05
    6    0.29

The rest of the freqs. are positive. Any help please? I have worked well
with ground state opt, but need guidance for excited state. How do I know
which atoms contribute to this?
Moreover this optimization is way too slow compared to the ground state.
That is another reason why I want to understand this properly and then move
further.

Regards,

-- 
*Dr. Siddheshwar chopra,*


*M.Sc., Ph.D (Physics)Assistant Professor (Physics),*
*Amity University, Noida, India.*
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