Multipole decomposition in discrete dipole approximation

摘要

In the framework of discrete dipole approximation, multipole decomposition of extinction and scattering spectra by nanoparticles of arbitrary shape is discussed. The method is applied to cubic Si nanoparticles with resonant multipole responses in the visible spectral range. It is demonstrated that there is a spectral band where Si cubic nanoparticles support a magnetic quadruple mode and scatter light as a point-like magnetic quadrupole.