Raman spectra of benzene derivatives adsorbed on metal substrates

We study the molecular orientations of several benzene derivatives on large Ag and Au clusters via first-principles calculations. We find the lowest-energy structures, several local minima and the diffusion barriers for benzene, nitrobenzene, 2,4-dinitrotoluene (DNT) and 1,4-benzenedimethanethiol (BDMT). The theoretical calculations are compared to experimental measurements of SERS for 2,4-DNT and 1,4-BDMT on Ag and Au coated dielectric nanowires.