Discrete dipole approximation

The discrete dipole approximation (DDA), also known as the coupled dipole approximation, is a numerical method for computing the scattering and absorption of electromagnetic radiation by particles of arbitrary shape and composition. The method represents a continuum target as a finite array of small, polarizable dipoles, and solves for their interactions with the incident field and with each other.

Source: Wikipedia — Discrete dipole approximation (CC BY-SA 4.0)