The interactions between molecules and metal nanoparticles lead to unusal optical properties that have applications for energy harvesting and chemical sensors.An important property of metal nanoparticles is their ability to generate very strong local fields at the surface of the particle due to the plasmon excitation.The local field can significantly alter the optical properties of molecules.Our group has developed an atomistic electrodynamics model and combined it with time-dependent DFT.This discrete interaction model/quantum mechanics (DIM/QM) method represents the nanoparticle atomistically,thus enables the modeling of the influence of the local environment of a nanoparticle surface on the optical properties of a molecule.