On the Importance of Local-Field Corrections for Polarizable Particles on a Finite Lattice

We investigate the influence of local-field effects on the electromagnetic response of a collection of dipoles. We derive the local-field corrected static polarizability for a collection of dipoles in the case of a scatterer with uniform depolarization. We then use this correction within the discrete dipole approximation to study the scattering of an electromagnetic wave by a spherical particle. The local-field correction leads to a new formulation of the discrete dipole approximation that is exact in the long-wavelength limit and more accurate at finite frequencies. We also discuss the feasibility of a generalization of the local-field correction to arbitrary scatterers.