  This study examines the Raman scattering and charge transfer properties of
molecules adsorbed on the surface of a tetrahedral Au$_{120}$ nanoparticle
based on the time-dependent density functional tight-binding (TD-DFTB) method.
We study Raman scattering (SERS) enhancements for pyridine where the molecule
is adsorbed either on the tip (V complex) or surface (S complex) of the
nanoparticle. The scattering intensity is enhanced by a factor of 3-15 due to
chemical effects while significantly larger enhancements (in the order of
10$^2$-10$^4$) are observed for plasmon resonance excitation at an energy of
2.5 eV depending on the adsorption site. Furthermore, we demonstrate charge
transfer between the nanoparticle and a fullerene-based molecule after pulsed
excitation of the plasmon resonance which shows how plasmon excitation can lead
to negative molecular ion formation. All of these results are consistent with
earlier studies using either TD-DFT theory or experimental measurements.
