“Plasmonic materials: At the interface of quantum chemistry and classical electrodynamics”
Plasmons are collective excitations of electrons, in which the excited state involves a superposition (entanglement) of electron/hole excitations. This is in contrast with the low lying excited states of most molecules where the excitations correspond to transfer of an electron from an occupied to an unoccupied orbital. Plasmon excited states exist in all molecules and solids, but they are most commonly studied in silver and gold nanoparticles, there they are responsible for the vivid colors of colloidal silver and gold. It is possible to describe the optical properties of plasmonic materials using classical electrodynamics with an empirical dielectric function, and this is extremely useful for applications in nanoscience, as it enables the description of metal structures that are hundreds of nm in size. However some properties involving the transfer of charge between the metal and adsorbed molecules cannot be described this way, and it is necessary to use quantum chemistry methods instead. The talk will describe the interplay between classical and quantum descriptions of plasmonic systems for applications that range from the optical properties of silver and gold clusters to plasmon driven photocatalysis.
