Accuracy of the Skin Depth Correction for Metallic Nanoparticle Polarizability

Dipole approximations are commonly used in calculations of light scattering and optical forces acting on nanoparticles. The scattered field strength is proportional to particle volume. For the past three decades, many researchers have used an effective volume based on skin depth when dealing with metallic nanoparticles, instead of the full volume. By comparing several dipole models to Mie scattering and finite difference time domain simulations, we show that it is more accurate to use the full volume because the complex relative permittivity of the metal already accounts for its skin depth.