The computation of electrochemical systems is very challenging because of the many
variables involved.1 Among them, the effect of the electrode potential is particularly
complex to be introduced in atomistic models. In this work, we propose a model where
the surface excess of charge has been modelled with the tetrahedral-like clusters
[Ag19]+, [Ag20]0 and [Ag19]-. We then modulate the effect of other surface charges
implicitly as an external electric field and correlated a calculated magnitude like the
electric charge on the adsorbate with the electrode potential, a purely experimental
one.
This model is tested with the potential-dependent Surface-Enhanced Raman Scattering
(SERS) of pyridine. Namely, we investigated the changes in the Raman shifts and
relative intensities due to the potential, and evaluated the different contributions
(electromagnetic, charge-transfer) to the SERS spectra. Our preliminary results nicely
reproduce the experimental trends and reveal that enhancement factors up to 107 are
achieved when the charge-transfer state interact with the bright local excitations of the
metal cluster.
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