Time domain simulations of chemical bonding effects in surface-enhanced spectroscopy.

The atom-centered density-matrix propagation method is used to illustrate how time-dependent conformational changes affect the electronic structure and derived spectroscopic properties of a prototypical finite metal cluster-bound π-conjugated organic complex, Ag7-benzenethiol. We establish that there is considerable conformational flexibility to the model structure, even at relatively low temperatures, which influences the predicted spectroscopic properties. Namely, the computed electron densities, dipoles, and polarizabilities are all dictated by torsional motion which controls the coupling between the π-framework of the chemisorbed molecular system and the cluster.