Seminarium "Modeling of Complex Systems"

Plasmonics is the emerging research field, indicating the ability of materials to control light at nanoscale range to examine them for various properties and functions. Originally, Ag, Au, and Al metals were used as plasmonic materials but they did not perform well because of radiative losses, high amount of energy dissipation, and their poor tuning ability. To overcome these problems for efficient plasmonic applications, a class of two-dimensional (2D) materials is proposed which presents a significant light-matter interaction phenomenon resulting in efficient quantum confinement effects. In the present talk, we report theoretical studies of nonlinear plasmonics in nanoflakes of graphene and MXenes (titanium carbides Ti2C). We consider flakes consisting of a few thousands of atoms of triangular and hexagonal shape, paying attention to the morphology of edges and typical types of intrinsic defects. The modelling procedure involves time dependent density functional theory to compute electronic structure, electronic excitations, dielectric function and electron energy loss (EEL) function to determine energies of plasmon excitations. Then, the many-body time dependent density matrix approach is used to perform computations of collective electronic excitations and the system's response to the electromagnetic field. The studies indicate that the nonlinear polarizabilities of nanostructures originating from 2D materials can be electrically tuned and might surpass those of typical metal nanoparticles of similar size.