Numerical modelling of the interaction of nanoparticles with electromagnetic waves

The paper is focused on the numerical modelling of the interaction between electromagnetic fields and metallic nanoparticle. A full-wave solution of the field problem is modelled in terms of an integral equation where the unknown is the displacement current. For treating nanoparticles having sizes smaller than the relevant wavelength, particular care is devoted to the choice of the discrete representation of the unknown in view of the condition number of the resulting linear system of equations. A critical analysis of the issues to be considered for developing a proper numerical model of the problem is presented. Specifically, it is shown that the electric field inside the nanoparticle is not purely irrotational, as usually assumed in the widespread models based on the electrostatic approximation. The proposed formulation is applied for the first time to the problem of evaluating the interaction between electromagnetic fields and metallic nanoparticle.