Ab initio simulation of optical absorption in noble metals and plasmonic ceramics*

Modeling the complex dielectric function of metallic system is the key to understand their applications as plasmonic materials. While traditional plasmonic materials such as noble metals (Au, Ag) have been well-studied by experiments, theoretical characterizations of these materials, as well as emerging new plasmonic ceramics that can endure extreme conditions, have been limited to merely the semi-classical Drude model. However, in the infrared region, phonon-assisted absorption is an important contribution to the total absorption in metallic systems due to the presence of large amount of free carriers. In this poster, we will present our work on the characterization of optical response of metals and plasmonic ceramics by considering phonon-assisted indirect transitions, direct transitions, and resistive absorption. Our calculated optical spectra of Ag, Au, and TiN show excellent agreement with experiment. Our work provides a tool to systematically characterize optical response of metals from first principles, enabling rational design of new plasmonic materials.