A second order approximation for the quasistatic properties of a nanoegg

Breaking the symmetry in plasmonic nanoparticles offers additional degrees of freedom that can be utilized to increase the tunability of such nanoparticles. Metallic shells with non-concentric dielectric cores possess such properties, where the core displacement affects the wavelength at which plasmon resonance occurs. It remains important to have analytical formulation for the properties of such nanoparticles especially for the design and optimization for nanoparticle based devices. In this paper we present an analytical formulation for capturing the resonant properties of asymmetrical nanoparticles based on the quasistatic approximation of Maxwell´s equations.