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The control and tuning of the optical properties of materials and the localization of electromagnetic energy are long standing quests for scientists. Not only it allows to design new classes of adaptive devices such as smart windows but also to perform surface enhanced vibrational spectroscopies such a SERS. Behind all these applications, fundamental questions are still debated : what is the role of electron correlation in the optical response ? How to include to contribution of crystal field in the dielectric response of complex system ? How the local electro-magnetic field influence the optical absorption and the SERS activity ? For metallic nanostructured systems, the optical properties are directly related to collective electronic excitation (plasmons) and they depend mainly on the composition, shape and size of the system. Doped semiconductors such as Indium Tin Oxide have been also shown to display active plasmon, i.e., optical excitations that can be controlled by an external stimulus such as static electric potential [1]. In 2D materials like graphene, the electrostatic doping is a commonly used to modify the optical response due to the low density of state at the Fermi energy. Moreover, topological corrugation, anisotropy [2], chemical doping [3] and electrostatic coupling in vanderwaals heterostructures plays very specific roles on the optical responses. Graphene nanodots and molecular PAH also supported plasmon excitation and electrochromic behavior. In this presentation, based on numerical simulations, we analyze the optical properties of these compounds and we discuss the influence of electrostatic coupling and charging effects. We emphasized the role of the electron correlation and of the local field in classical, semi-empirical and ab-initio methods. [1] A. Maho et al. Solar Energy Materials and Solar Cells 200 (2019) 110014 [2] B. Majerus et al. Phys. Rev. B 98 (2018) 125419 [3] F. Joucken et al. Phys. Rev. Mat. 3 (2019) 110301 |
