  The main aim of this study is to scrutinize promising plasmonic materials by
understanding their electronic structure and correlating them to the optical
properties of selected refractory materials. For this purpose, the electronic
and optical properties of the conductive ceramics TiC, ZrC, HfC, TaC, WC, TiN,
ZrN, HfN, TaN, and WN are studied systematically by means of first-principles
density functional theory. A full ab initio procedure to calculate plasma
frequency from the electronic band structure is discussed. The dielectric
functions are calculated by including electronic interband and intraband
transitions. Our calculations confirm that transition metal nitrides, such as
TiN, ZrN, and HfN, are the strongest candidates, exhibiting performance
comparable to that of conventional noble metals in the visible to the
near-infrared regions. On the other hand, carbides are not suitable for
plasmonic applications because they show very large losses in the same regions.
From our calculated dielectric functions, the scattering and absorption
efficiencies of nanoparticles made of these refractory materials are evaluated.
It is revealed that TiN and TaC are the best candidate materials for
applications in photothermal energy conversion over a broad spectral region.
Furthermore, quality factors for localized surface plasmon resonance and
surface plasmon polaritons are calculated to compare quantitative performances,
and ZrN and HfN are found to be comparable to conventional plasmonic metals
such as silver and gold
