  We report a time-dependent density functional based tight-binding (TD-DFTB)
scheme for the calculation of UV/Vis spectra, explicitly taking into account
the excitation of nuclear vibrations via the adiabatic Hessian Franck-Condon
(AH|FC) method with a harmonic approximation for the nuclear wavefunction. The
theory of vibrationally resolved UV/Vis spectroscopy is first summarized from
the viewpoint of TD-DFTB. The method is benchmarked against time-dependent
density functional theory (TD-DFT) calculations for strongly dipole allowed
excitations in various aromatic and polar molecules. Using the recent 3ob:freq
parameter set of Elstner's group, very good agreement with TD-DFT calculations
using local functionals was achieved.
