Modified Combined Tangential Formulation for Stable and Accurate Analysis of Plasmonic Structures

We consider a modified combined tangential formulation (MCTF) for stable and accurate analysis of plasmonic problems involving metallic objects modeled as penetrable bodies. For a wide range of negative real permittivity values, corresponding to varying characteristics of metals at THz, infrared, and visible frequencies, MCTF provides accurate solutions in comparison to the conventional formulations for penetrable objects. We further show that, for structures with subwavelength dimensions, penetrable models formulated with MCTF can be essential for accurate analysis, rather than the perfectly conducting formulations, even at the lower THz frequencies.