Subject: TD-DFT

From: "Guillaumont 4405821 Dominique" <[email-masked]>
Date: Thu, 8 Jul 1999 19:03:09 +0900

Dear all,

I would have 2 questions concerning TD-DFT method.
I'm trying to calculate electronic excited states with TD-DFT implemented in
gaussian for organic dyes with lowest excited states of clear valence type.

My first question concerns the choice of the geometry, is it more justified to
use an experimental geometry which should be closer to reality or to use a
geometry optimized at the DFT level which should be more consistent with the
calculations ?

My second question concerns the choice of the functional, when going from a
hybrid (B3P86, B3LYP) to a non-hybrid functional (BP86,BLYP), the energy are
shifted from 1000 to 5000 cm-1, and also the relative order of some excited
states change, especially for the triplet states.Hybrid functionals reproduce
better experimental spectra but give too high energies for triplet states. Which
are the reasons other than the correct reproduction of experimental datas to
chose a functional ?

Thanks in advance,

Dominique Guillaumont

[email-masked]