DDSCAT 7.3 is a freely available open-source Fortran-90 software package applying the “discrete
dipole approximation” (DDA) to calculate scattering and absorption of electromagnetic waves by targets
with arbitrary geometries and complex refractive index. The targets may be isolated entities (e.g., dust
particles), but may also be 1-d or 2-d periodic arrays of “target unit cells”, which can be used to study
absorption, scattering, and electric ?elds around arrays of nanostructures.
